[cl-gtk2.git] / doc / gobject.texi

\input texinfo  @c -*-texinfo-*-
@c %**start of header (This is for running texinfo on a region.)
@setfilename gobject.info
@settitle CL-Gtk2-GObject
@c %**end of header (This is for running texinfo on a region.)

@c @documentencoding utf-8

@macro Function {args}
@defun \args\
@end defun
@end macro

@macro Macro {args}
@defmac \args\
@end defmac
@end macro

@macro Accessor {args}
@deffn {Accessor} \args\
@end deffn
@end macro

@macro GenericFunction {args}
@deffn {Generic Function} \args\
@end deffn
@end macro

@macro ForeignType {args}
@deftp {Foreign Type} \args\
@end deftp
@end macro

@macro Variable {args}
@defvr {Special Variable} \args\
@end defvr
@end macro

@macro Condition {args}
@deftp {Condition Type} \args\
@end deftp
@end macro

@macro cffi
@acronym{CFFI}
@end macro

@macro impnote {text}
@quotation
@strong{Implementor's note:} @emph{\text\}
@end quotation
@end macro

@c Info "requires" that x-refs end in a period or comma, or ) in the
@c case of @pxref.  So the following implements that requirement for
@c the "See also" subheadings that permeate this manual, but only in
@c Info mode.
@ifinfo
@macro seealso {name}
@ref{\name\}.
@end macro
@end ifinfo

@ifnotinfo
@alias seealso = ref
@end ifnotinfo

@c Typeset comments in roman font for the TeX output.
@iftex
@alias lispcmt = r
@end iftex
@ifnottex
@alias lispcmt = asis
@end ifnottex

@c My copy of makeinfo is not generating any HTML for @result{} for
@c some odd reason. (It certainly used to...)
@ifhtml
@macro result
=>
@end macro
@end ifhtml

@c Similar macro to @result. Its purpose is to work around the fact
@c that ⇒ does not work properly inside @lisp.
@ifhtml
@macro res
@html
⇒
@end html
@end macro
@end ifhtml

@ifnothtml
@alias res = result
@end ifnothtml

@c ============================= Macros =============================


@c Show types, functions, and concepts in the same index.
@syncodeindex tp cp
@syncodeindex fn cp

@titlepage
@title CL-GTK2
@subtitle A Common Lisp binding for Gtk+
@subtitle GObject
@author Dmitry Kalyanov
@end titlepage

@contents

@ifnottex
@node Top
@top cl-gtk2-gobject
@end ifnottex

@menu
* Introduction::
* Installation::
* GType designator::
* Type hierarchy and type relations::
* Object types information::
* Enum types information::
* Using GValues::
* Stable pointers::
* Closures::
* GObject low-level::
* GObject high-level::
* Subclassing GObjects and implementing GInterfaces::
* GBoxed::
* Generating type definitions by introspection::
@end menu

@node Introduction
@chapter Introduction

GObject is a part of GLib library that implements the type system. The CL-GTK2-GObject is a Common Lisp binding for relevant parts of GObject.

The purpose of CL-GTK2-GObject is to ease the creation of binding for libraries based on GObject.

Please bear in mind that this is the documentation for a work-in-progress library and is a snapshot of current situation. API and functionality may (and will) change. Largely unfinished parts are working with GBoxed types, subclassing GObjects and implementing GInterfaces.

CL-GTK2-GObject is logically split into several layers:
@itemize
@item FFI code. FFI (foreign functions interface) layer is a glue between Lisp code and @code{libglib}, @code{libgobject}, @code{libgthread}. This code includes basic wrapper around GType designator (it is used everywhere and should be defined first) and definitions of foreign structures and imports foreign functions.
@item Low-level GObject integration. These are facilities provided by GObject that capture specific aspects of type system, object system and cross-language runtime. This includes types information, GValues (generic containers for value of any type supported by GObject type system), closures, means to create and use objects. This layer also includes some non-GObject facilities: stable pointers.
@item High-level GObject integration. This layer includes support for interoperability between CLOS and GObject and automatic generation of corresponding definitions.
@end itemize

Naturally, users of CL-GTK2-GObject should use the high-level GObject integration, but occasionaly it may be necessary to use lower-level functionality.

@node Installation
@chapter Installation

CL-GTK2-GObject comes as a part of CL-GTK2 bindings that are avaiable at its @uref{http://common-lisp.net/project/cl-gtk2/,,website}.

To use the CL-GTK2-GObject, download and install CL-GTK2 bindings and load the ASDF system @code{cl-gtk2-glib}.

CL-GTK2-GObject defines two packages: @code{gobject} and @code{gobject.ffi}. The @code{gobject.ffi} package contains definitions for low-level CFFI imports. The @code{gobject} package contains symbols for external API of this GObject binding.

@node GType designator
@chapter GType designator

@menu
* g-type-string::
* g-type-numeric::
@end menu

GObject is an object system based on GType type system. Types in it are identified by an integer value of type @code{GType}. In @code{cl-gtk2-gobject}, types are identified by GType designators. GType designator is an integer (equal to corresponding GType identifier) or a string (equal to the name of corresponding type). The important difference between GType and GType designator is that GType values may change between program runs (all GTypes except fundamental GTypes will change values), but string GType designators do not change (because names of types do not change). As such, if ever GType must be saved in a code, string GType designator should be preferred.

An example of GType designator is a string @code{"GObject"} and the numeric value 80 that corresponds to it.

Some of the types are fundamental and have constant integer values. They are identified by constants (strings in parentheses are corresponding type names):
@itemize
@item @code{+g-type-invalid+}. An invalid GType used as error return value in some functions which return a GType.
@item @code{+g-type-void+} ("void"). A fundamental type which is used as a replacement for the C @code{void} return type.
@item @code{+g-type-interface+} ("GInterface"). The fundamental type from which all interfaces are derived.
@item @code{+g-type-char+} ("gchar"). The fundamental type corresponding to gchar. The type designated by @code{+g-type-char+} is unconditionally an 8-bit signed integer. This may or may not be the same type a the C type @code{gchar}.
@item @code{+g-type-uchar+} ("guchar"). The fundamental type corresponding to @code{guchar}.
@item @code{+g-type-boolean+} ("gboolean"). The fundamental type corresponding to @code{gboolean}.
@item @code{+g-type-int+} ("gint"). The fundamental type corresponding to @code{gint}.
@item @code{+g-type-uint+} ("guint"). The fundamental type corresponding to @code{guint}.
@item @code{+g-type-long+} ("glong"). The fundamental type corresponding to @code{glong}.
@item @code{+g-type-ulong+} ("gulong"). The fundamental type corresponding to @code{gulong}.
@item @code{+g-type-int64+} ("gint64"). The fundamental type corresponding to @code{gint64}.
@item @code{+g-type-uint64+} ("guint64"). The fundamental type corresponding to @code{guint64}.
@item @code{+g-type-enum+} ("GEnum"). The fundamental type from which all enumeration types are derived.
@item @code{+g-type-flags+} ("GFlags"). The fundamental type from which all flags types are derived.
@item @code{+g-type-float+} ("gfloat"). The fundamental type corresponding to @code{gfloat}.
@item @code{+g-type-double+} ("gdouble"). The fundamental type corresponding to @code{gdouble}.
@item @code{+g-type-string+} ("gchararray"). The fundamental type corresponding to null-terminated C strings.
@item @code{+g-type-pointer+} ("gpointer"). The fundamental type corresponding to @code{gpointer}.
@item @code{+g-type-boxed+} ("GBoxed"). The fundamental type from which all boxed types are derived.
@item @code{+g-type-param+} ("GParam"). The fundamental type from which all GParamSpec types are derived.
@item @code{+g-type-object+} ("GObject"). The fundamental type for GObject.
@end itemize

Functions @ref{g-type-string} and @ref{g-type-numeric} return the numeric and string representations of GType designators (given any of them).

Invalid type (the GType that does not exist) is identified as a 0 or @code{NIL}.

@example
(g-type-numeric "GObject") @result{} 80
(g-type-numeric 80) @result{} 80
(g-type-string "GObject") @result{} "GObject"
(g-type-string 80) @result{} "GObject"
(g-type-numeric "GtkWidget") @result{} 6905648 ;;Will be different on each run
@end example

@node g-type-string
@section g-type-string

@code{(g-type-string g-type-designator) @result{} name}

@table @var
@item @var{g-type-designator}
The GType designator for the GType
@item @var{name}
The name of GType
@end table

Returns the name of GType.

@node g-type-numeric
@section g-type-numeric

@code{(g-type-numeric g-type-designator) @result{} GType}

@table @var
@item @var{g-type-designator}.
The GType designator for the GType.
@item @var{GType}
The numeric identifier of GType
@end table

Returns the numeric identifier of GType

@node Type hierarchy and type relations
@chapter Type hierarchy and type relations

@menu
* g-type-children::
* g-type-parent::
* g-type-fundamental::
* g-type-depth::
* g-type-next-base::
@end menu

GTypes are organized into hierarchy. Each GType (except fundamental types) has a parent type and zero or more children types. Parent of GType identified by @code{g-type-parent} function and its children are identified by @code{g-type-children} function.

There are functions to query some specific information:
@itemize
@item @code{g-type-fundamental} retrieves the fundamental type for given type
@item @code{g-type-depth} calculates the depth of the type in type hierarchy
@item @code{g-type-next-base} calculates the first step in the path from base type to descendent type
@end itemize

@node g-type-children
@section g-type-children

@code{(g-type-children type) @result{} children}
@table @var
@item @var{type}
A GType designator
@item @var{children}
A list of GType designators
@end table

Returns the list of descendent types.

Example:
@example
(g-type-children "GtkButton")
@result{}
("GtkToggleButton" "GtkColorButton" "GtkFontButton" "GtkLinkButton" "GtkScaleButton")
@end example

@node g-type-parent
@section g-type-parent

@code{(g-type-parent type) @result{} parent}

@table @var
@item @var{type}
A GType designator
@item @var{parent}
A GType designator
@end table

Returns the parent of @code{type}.

Example:
@example
(g-type-parent "GtkToggleButton")
@result{}
"GtkButton"
@end example
@node g-type-fundamental
@section g-type-fundamental

@code{(g-type-fundamental type) @result{} fundamental-type}

@table @var
@item @var{type}
A GType designator
@item @var{fundamental-type}
A GType designator for one of the fundamental types
@end table

Returns the fundamental type that is the ancestor of @code{type}.

Example:
@example
(g-type-fundamental "GtkButton") @result{} "GObject"

(g-type-fundamental "GtkWindowType") @result{} "GEnum"

(g-type-fundamental "GdkEvent") @result{} "GBoxed"
@end example

@node g-type-depth
@section g-type-depth

@code{(g-type-depth type) @result{} depth}

@table @var
@item @var{type}
A GType designator
@item @var{depth}
An integer
@end table

Returns the depth of the @code{type}. Depth is the number of types between the @code{type} and its fundamental types (including both @code{type} and its fundamental type). Depth of a fundamental type equals to 1.

Example:
@example
(g-type-depth "GObject") @result{} 1
(g-type-depth "GInitiallyUnowned") @result{} 2
@end example

@node g-type-next-base
@section g-type-next-base

@code{(g-type-next-base leaf-type root-type) @result{} base-type}

@table @var
@item @var{leaf-type}
A GType designator
@item @var{root-type}
A GType designator
@item @var{base-type}
A GType designator
@end table

Returns the next type that should be traversed from @code{root-type} in order to reach @code{leaf-type}. E.g., given type hierarchy:
@example
+ GObject
 \
  + GInitiallyUnowned
   \
    + GtkObject
    |\
    | + GtkAdjustment
     \
      + GtkWidget
       \
        + GtkContainer
         \
          + GtkTable
@end example

the following will be returned:

@example
(g-type-next-base "GtkTable" "GObject") @result{} "GInitiallyUnowned"
(g-type-next-base "GtkTable" "GInitiallyUnowned") @result{} "GtkObject"
(g-type-next-base "GtkTable" "GtkObject") @result{} "GtkWidget"
(g-type-next-base "GtkTable" "GtkWidget") @result{} "GtkContainer"
(g-type-next-base "GtkTable" "GtkContainer") @result{} "GtkTable"
@end example

@node Object types information
@chapter Object types information
@menu
* g-class-property-definition::
* class-properties::
* class-property-info::
* interface-properties::
* signal-info::
* type-signals::
* parse-signal-name::
* query-signal-info::
* g-type-interfaces::
* g-type-interface-prerequisites::
@end menu

GObject classes and interfaces have properties that can be queried with @code{class-properties}, @code{class-property-info} and @code{interface-properties}. These functions represent information about properties with instances of @code{g-class-property-definition} structure.

Information about signals can be queries with @code{type-signals}, @code{parse-signal-name} and @code{query-signal-info} functions. Information is returned within instances of @code{signal-info} structures.

@node g-class-property-definition
@section g-class-property-definition

@example
(defstruct g-class-property-definition
  name
  type
  readable
  writable
  constructor
  constructor-only
  owner-type)
@end example

@table @var
@item @var{name}
A string that names the property
@item @var{type}
A GType designator. Identifies the type of the property
@item @var{readable}
A boolean. Identifies whether the property can be read
@item @var{writable}
A boolean. Identifies whether the property can be assigned
@item @var{constructor}
A boolean. Identifies whether constructor of object accepts this property
@item @var{constructor-only}
A boolean. Identifies whether this property may only be set in constructor, not in property setter
@item @var{owner-type}
A GType designator. Identifies the type on which the property was defined.
@end table

This structure identifies a single property. Its field specify attributes of a property.

Structures of this type have shortened print syntax:
@example
#<PROPERTY gchararray GtkButton.label (flags: readable writable constructor)> 
@end example

(When @code{*print-readably*} is T, usual @code{defstruct} print syntax is used)

This syntax specifies:
@itemize
@item type of property
@item the owner type of property
@item name of property
@item additional flags of property
@end itemize

@node class-properties
@section class-properties

@code{(class-properties type) @result{} properties}

@table @var
@item @var{type}
A GType designator. Specifies the object type (class)
@item @var{properties}
A list of @code{g-property-definition} structures.
@end table

This function returns the list of properties that are available in class @code{type}.

Example:
@example
(class-properties "GtkWidget")
@result{}
(#<PROPERTY gpointer GtkObject.user-data (flags: readable writable)>
 #<PROPERTY gchararray GtkWidget.name (flags: readable writable)>
 #<PROPERTY GtkContainer GtkWidget.parent (flags: readable writable)>
 #<PROPERTY gint GtkWidget.width-request (flags: readable writable)>
 #<PROPERTY gint GtkWidget.height-request (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.visible (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.sensitive (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.app-paintable (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.can-focus (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.has-focus (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.is-focus (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.can-default (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.has-default (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.receives-default (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.composite-child (flags: readable)>
 #<PROPERTY GtkStyle GtkWidget.style (flags: readable writable)>
 #<PROPERTY GdkEventMask GtkWidget.events (flags: readable writable)>
 #<PROPERTY GdkExtensionMode GtkWidget.extension-events (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.no-show-all (flags: readable writable)>
 #<PROPERTY gboolean GtkWidget.has-tooltip (flags: readable writable)>
 #<PROPERTY gchararray GtkWidget.tooltip-markup (flags: readable writable)>
 #<PROPERTY gchararray GtkWidget.tooltip-text (flags: readable writable)>
 #<PROPERTY GdkWindow GtkWidget.window (flags: readable)>)
@end example

@node class-property-info
@section class-property-info
@code{(class-property-info type property-name) @result{} property}

@table @var
@item @var{type}
A GType designator
@item @var{property-name}
A string naming the property
@item @var{property}
An instance of @code{g-property-definition} structure
@end table

Returns the property information for a single property.

Example:
@example
(class-property-info "GtkButton" "label")
@result{}
#<PROPERTY gchararray GtkButton.label (flags: readable writable constructor)>
@end example

@node interface-properties
@section interface-properties

@code{(interface-properties type) @result{} properties}

@table @var
@item @var{type}
A GType designator
@item @var{properties}
A list of @code{g-property-definition} structures
@end table

This function returns the list of properties that are available in interface @code{type}.

Example:
@example
(interface-properties "GtkFileChooser")
@result{}
(#<PROPERTY GtkWidget GtkFileChooser.extra-widget (flags: readable writable)>
 #<PROPERTY gboolean GtkFileChooser.use-preview-label (flags: readable writable)>
 #<PROPERTY gboolean GtkFileChooser.preview-widget-active (flags: readable writable)>
 #<PROPERTY gboolean GtkFileChooser.show-hidden (flags: readable writable)>
 #<PROPERTY gchararray GtkFileChooser.file-system-backend (flags: writable constructor-only)>
 #<PROPERTY GtkFileChooserAction GtkFileChooser.action (flags: readable writable)>
 #<PROPERTY GtkFileFilter GtkFileChooser.filter (flags: readable writable)>
 #<PROPERTY gboolean GtkFileChooser.select-multiple (flags: readable writable)>
 #<PROPERTY GtkWidget GtkFileChooser.preview-widget (flags: readable writable)>
 #<PROPERTY gboolean GtkFileChooser.local-only (flags: readable writable)>
 #<PROPERTY gboolean GtkFileChooser.do-overwrite-confirmation (flags: readable writable)>)
@end example

@node signal-info
@section signal-info

@example
(defstruct signal-info
  id
  name
  owner-type
  flags
  return-type
  param-types
  detail)
@end example

@table @var
@item @var{id}
An integer - the identifier of a signal
@item @var{name}
Name of a signal
@item @var{owner-type}
A GType designator identifying the type on which the signal was defined
@item @var{flags}
A list of keywords of type @code{'(member :run-first :run-last :run-cleanup :no-recurse :detailed :action :no-hooks)}. Specifies the attributes of a signals
@item @var{return-type}
The return type of a signal (and signal handlers)
@item @var{param-types}
A list of GType designators that specify the types of signal parameters
@item @var{detail}
A string. Specifies the "detail" part of a signal name. E.g., @code{"label"} for signal @code{"notify::label"}.
@end table

When @code{*print-readably*} is nil, the following print syntax is used:
@example
#<Signal [#1] void GObject.notify::label(GParam) [RUN-FIRST, NO-RECURSE, DETAILED, ACTION, NO-HOOKS]>
#<Signal [#54] gboolean GtkWidget.proximity-in-event(GdkEvent) [RUN-LAST]>
#<Signal [#64] void GtkWidget.drag-data-received(GdkDragContext, gint, gint, GtkSelectionData, guint, guint) [RUN-LAST]>
#<Signal [#8] void GtkObject.destroy() [RUN-CLEANUP, NO-RECURSE, NO-HOOKS]>
@end example

This syntax specifies:
@itemize
@item the signal id
@item signal return type
@item owner type
@item signal name
@item detail
@item list of types of parameters
@item flags
@end itemize

@node type-signals
@section type-signals
@code{(type-signals type &key (include-inherited t)) @result{} signals}
@table @var
@item @var{type}
A GType designator
@item @var{signals}
A list of @code{signal-info} structures
@item @var{include-inherited}
A boolean that specifies whether to include signals defined on this type or also on ancestor types.
@end table

Returns the list of signals that are available in type @code{type}.

Example:
@example
(type-signals "GtkLabel" :include-inherited nil)
@result{}
(#<Signal [#138] void GtkLabel.move-cursor(GtkMovementStep, gint, gboolean) [RUN-LAST, ACTION]>
 #<Signal [#139] void GtkLabel.copy-clipboard() [RUN-LAST, ACTION]>
 #<Signal [#140] void GtkLabel.populate-popup(GtkMenu) [RUN-LAST]>)
@end example

@node parse-signal-name
@section parse-signal-name

@code{(parse-signal-name type signal-name) @result{} signal}

@table @var
@item @var{type}
A GType designator that has the signal.
@item @var{signal-name}
A string that identifies the signal.
@item @var{signal}
A list @code{signal-info} structures.
@end table

Parses the signal name and returns the corresponding information. @code{signal-name} may include the detail part.

Example:
@example
(parse-signal-name "GObject" "notify::label")
@result{}
#<Signal [#1] void GObject.notify::label(GParam) [RUN-FIRST, NO-RECURSE, DETAILED, ACTION, NO-HOOKS]>
@end example

@node query-signal-info
@section query-signal-info
@code{(query-signal-info signal-id) @result{} signal}
@table @var
@item @var{signal-id}
An integer identifying the signal
@item @var{signal}
An instance of @code{signal-info} structure
@end table

Retrieves the signal information by its id.

Example:
@example
(query-signal-info 73)
@result{}
#<Signal [#73] gboolean GtkWidget.show-help(GtkWidgetHelpType) [RUN-LAST, ACTION]>
@end example

@node g-type-interfaces
@section g-type-interfaces

@code{(g-type-interfaces type) @result{} interfaces}

@table @var
@item @var{type}
A GType designator
@item @var{interfaces}
A list of GType designators
@end table

Returns the list of interfaces that @code{type} implements.

Example:
@example
(g-type-interfaces "GtkButton")
@result{}
("AtkImplementorIface" "GtkBuildable" "GtkActivatable")
@end example

@node g-type-interface-prerequisites
@section g-type-interface-prerequisites

@code{(g-type-interface-prerequisites type) @result{} types}

@table @var
@item @var{type}
A GType designator of interface
@item @var{types}
A list of GType designators specifying the interface prerequisites
@end table

Returns the prerequisites of an interface @code{type}. Prerequisite is a type that should be an ancestor of a type implementing interface @code{type}.

Example:
@example
(g-type-interface-prerequisites "GtkCellEditable")
@result{}
("GtkObject" "GtkWidget")
@end example

@node Enum types information
@chapter Enum types information
@menu
* enum-item::
* flags-item::
* get-enum-items::
* get-flags-items::
@end menu

Enum types have items that can be listed with @code{get-enum-items} function. This information is exposed within instances of @code{enum-item} structure.

Flags types (flags is a kind of enum whose values can be combined) have items that can be queried with @code{get-flags-items} function. This information is exposed within instances of @code{flags-item} structure.

@node enum-item
@section enum-item
@example
(defstruct enum-item
  name value nick)
@end example

@table @var
@item @var{name}
A string - name of enum item
@item @var{value}
An integer - numeric value of enum item
@item @var{nick}
A string - short name of an enum item
@end table

Structure @code{enum-item} represents a single item of an enumeration type.

Example:
@example
#S(ENUM-ITEM :NAME "GTK_WINDOW_TOPLEVEL" :VALUE 0 :NICK "toplevel")
@end example

@node flags-item
@section flags-item
@example
(defstruct flags-item
  name value nick)
@end example

@table @var
@item @var{name}
A string - name of flags item
@item @var{value}
An integer - numeric value of flags item
@item @var{nick}
A string - short name of an flags item
@end table

Structure @code{flags-item} represents a single item of an flags type.

Example:
@example
#S(FLAGS-ITEM
   :NAME "GDK_POINTER_MOTION_HINT_MASK"
   :VALUE 8
   :NICK "pointer-motion-hint-mask")
@end example

@node get-enum-items
@section get-enum-items

@code{(get-enum-items type) @result{} items}

@table @var
@item @var{type}
A GType designator of an enum type
@item @var{items}
A list of @code{enum-item} structures
@end table

Returns a list of items in an enumeration

Example:
@example
(get-enum-items "GtkScrollType")
@result{}
(#S(ENUM-ITEM :NAME "GTK_SCROLL_NONE" :VALUE 0 :NICK "none")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_JUMP" :VALUE 1 :NICK "jump")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_STEP_BACKWARD" :VALUE 2 :NICK "step-backward")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_STEP_FORWARD" :VALUE 3 :NICK "step-forward")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_PAGE_BACKWARD" :VALUE 4 :NICK "page-backward")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_PAGE_FORWARD" :VALUE 5 :NICK "page-forward")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_STEP_UP" :VALUE 6 :NICK "step-up")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_STEP_DOWN" :VALUE 7 :NICK "step-down")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_PAGE_UP" :VALUE 8 :NICK "page-up")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_PAGE_DOWN" :VALUE 9 :NICK "page-down")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_STEP_LEFT" :VALUE 10 :NICK "step-left")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_STEP_RIGHT" :VALUE 11 :NICK "step-right")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_PAGE_LEFT" :VALUE 12 :NICK "page-left")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_PAGE_RIGHT" :VALUE 13 :NICK "page-right")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_START" :VALUE 14 :NICK "start")
 #S(ENUM-ITEM :NAME "GTK_SCROLL_END" :VALUE 15 :NICK "end"))
@end example

@node get-flags-items
@section get-flags-items

@code{(get-flags-items type) @result{} items}

@table @var
@item @var{type}
A GType designator of an flags type
@item @var{items}
A list of @code{flags-item} structures
@end table

Returns a list of items in an flags type

Example:
@example
(get-flags-items "GtkAttachOptions")
@result{}
(#S(FLAGS-ITEM :NAME "GTK_EXPAND" :VALUE 1 :NICK "expand")
 #S(FLAGS-ITEM :NAME "GTK_SHRINK" :VALUE 2 :NICK "shrink")
 #S(FLAGS-ITEM :NAME "GTK_FILL" :VALUE 4 :NICK "fill"))
@end example

@node Using GValues
@chapter Using GValues
@menu
* g-value-zero::
* g-value-init::
* g-value-unset::
* parse-g-value::
* set-g-value::
* Registering types::
@end menu

GValue is a generic container for arbitrary value of type supported by GType system. Refer to GObject documentation for more detailed information.

CL-GTK2-GOBJECT works with GValue as a foreign type @code{g-value}. Functions @code{g-value-zero}, @code{g-value-type}, @code{g-value-init}, @code{parse-g-value}, @code{set-g-value} are used to inspect and assign GValues. @code{g-value} is a CFFI foreign type that is used by all these functions. Pointer to foreign instance of this type is passed to them.

GValue is used whenever a value of unkown type should be passed. It is used in:
@itemize
@item Closure marshal functions
@item Property get and set functions
@end itemize

Example of usage:
@example
(cffi:with-foreign-object (gval 'g-value)
  (set-g-value gval "Hello" "gchararray" :zero-g-value t)
  (format t "~S~%" (parse-g-value gval))
  (g-value-unset gval))
@result{}
"Hello"
@end example

@node g-value-zero
@section g-value-zero
@code{(g-value-zero g-value)}
@table @var
@item @var{g-value}
A foreign pointer to GValue structure.
@end table

Initializes the GValue to "unset" state. Equivalent of the following initializer in C:
@example
GValue value = @{ 0 @};
@end example

Must be called before other functions that work with GValue (except @code{set-g-value} with keyword argument @code{:zero-g-value} set to true).

@node g-value-init
@section g-value-init

@code{(g-value-init value type)}
@table @var
@item @var{value}
A foreign pointer to GValue structure
@item @var{type}
A GType designator
@end table

Initializes the GValue to store instances of type @code{type}. Must be called before other functions operate on GValue (except @code{g-value-zero} and @code{set-g-value} with keyword argument @code{:g-value-init} set to true).

@node g-value-unset
@section g-value-unset
@code{(g-value-unset value)}
@table @var
@item @var{value}
A foreign pointer to GValue structure.
@end table

Unsets the GValue. This frees all resources associated with GValue.

@node parse-g-value
@section parse-g-value
@code{(parse-g-value value) @result{} object}
@table @var
@item @var{value}
A foreign pointer to GValue structure
@item @var{object}
A Lisp object
@end table

Retrieves the object from GValue structure.

@node set-g-value
@section set-g-value
@code{(set-g-value gvalue object type &key zero-g-value unset-g-value (g-value-init t))}

@table @var
@item @var{gvalue}
A foreign pointer to GValue structure
@item @var{object}
An object that is to be assigned to @code{gvalue}
@item @var{type}
A GType designator specifying what GType should be set
@item @var{unset-g-value}
A boolean specifying whether to call @code{g-value-unset} before assigment.
@item @var{zero-g-value}
A boolean specifying whether to call @code{g-value-zero} before assignment
@item @var{g-value-init}
A boolean specifying whether to call @code{g-value-init} before assignment
@end table

Assigns the @code{object} to the @code{gvalue}. When GValue is not used, call @code{g-value-unset} to deinitialize the @code{GValue}.

@node Registering types
@section Registering types

In order to be able to parse GValues and set them, it is necessary for GValue binding to know type mapping between GObject types and Lisp types. Type registration serves to this purpose.

GEnum and GFlags are mapped to CFFI @code{defcenum} and @code{defbitfield} types. Functions @code{register-enum-type} and @code{register-flags-type} add the type to the mapping.

@subsection
@code{(register-enum-type name type)}
@table @var
@item @var{name}
A string naming the GEnum type
@item @var{type}
A symbol - name of CFFI foreign enum type
@end table

Registers the @code{type} to be used for passing value of GEnum type @code{name} between GObject and Lisp.

Example:
@example
(defcenum text-direction
  :none :ltr :rtl)
(register-enum-type "GtkTextDirection" 'text-direction)
@end example

@subsection
@code{(register-flags-type name type)}
@table @var
@item @var{name}
A string naming the GFlags type
@item @var{type}
A symbol - name of CFFI foreign flags type
@end table

Registers the @code{type} to be used for passing value of GFlags type @code{name} between GObject and Lisp.

Example:
@example
(defcenum state-type
  :normal :active :prelight :selected :insensitive)
(register-enum-type "GtkStateType" 'state-type)
@end example

@node Stable pointers
@chapter Stable pointers
@menu
* allocate-stable-pointer::
* free-stable-pointer::
* stable-pointer-value::
* with-stable-pointer::
@end menu

Sometimes it is necessary to pass arbitrary Lisp object to C code and then receive it back. Stable pointer serve to this purpose. Stable pointer is an integer (that is passed to C code as a @code{void*} pointer) that is created on Lisp side by call to @code{allocate-stable-pointer} and can be dereferenced by Lisp side at any time by calling @code{stable-pointer-value}. Stable pointer exists and does not change its value until explicitly freed by calling @code{free-stable-poitner}. Convenience macro @code{with-stable-pointer} binds the stable pointer for the duration of its body.

@node allocate-stable-pointer
@section allocate-stable-pointer

@code{(allocate-stable-pointer thing) @result{} stable-pointer}

@table @var
@item @var{thing}
An arbitrary Lisp object
@item @var{stable-pointer}
A foreign pointer
@end table

Allocates a stable pointer to @code{thing}.

(Note: @var{stable-pointer} should not be dereferenced with @code{cffi:mem-ref}. It should only be dereferenced with @code{stable-pointer-value})

Example:
@example
(allocate-stable-pointer (lambda (x) (+ x 10)))
@result{}
#.(SB-SYS:INT-SAP #X00000002)

(stable-pointer-value *)
@result{}
#<FUNCTION (LAMBDA (X)) @{1004D016F9@}>

(free-stable-pointer **)
@result{}
NIL
@end example

@node free-stable-pointer
@section free-stable-pointer

@code{(free-stable-pointer stable-pointer)}

@table @var
@item @var{stable-pointer}
A foreign pointer that was created with @code{allocate-stable-pointer}.
@end table

Frees the stable pointer, enabling the garbage collector to reclaim the object.

Example:
@example
(allocate-stable-pointer (lambda (x) (+ x 10)))
@result{}
#.(SB-SYS:INT-SAP #X00000002)

(stable-pointer-value *)
@result{}
#<FUNCTION (LAMBDA (X)) @{1004D016F9@}>

(free-stable-pointer **)
@result{}
NIL
@end example

@node stable-pointer-value
@section stable-pointer-value

@example
(stable-pointer-value stable-pointer) @result{} thing
(setf (stable-pointer-value stable-pointer) thing)
@end example

@table @var
@item @var{stable-pointer}
A foreign pointer created by @code{allocate-stable-pointer}
@item @var{thing}
A Lisp object
@end table

Dereferences a @code{stable-pointer}, returning the stable pointer value. @code{stable-pointer-value} is a SETFable form, SETFing it sets the stable pointer's value to new value.

@node with-stable-pointer
@section with-stable-pointer

@code{(with-stable-pointer (ptr expr) &body body)}

@table @var
@item @var{ptr}
A variable that will be bound to the stable pointer
@item @var{expr}
An expression that will be evaluated once and its value will be bound to stable pointer's value
@end table

Executes the body with the @code{ptr} variable being bound to a stable pointer whose value is determined by @code{expr}.

Example:
@example
(with-stable-pointer (ptr (lambda (x) (+ x 10)))
  (print (stable-pointer-value ptr)))
;;Prints:
#<FUNCTION (LAMBDA (X)) @{1004807E79@}>
@end example

@node Closures
@chapter Closures

Closure are anonymous functions that capture their lexical environment.

GObject supports using closures (as instances of type GClosure) as signal handlers and in some other places where a function is expected. Function @code{create-g-closure} create closure from lisp function. The GClosure is finalized automatically when GObject no longer needs it (e.g., when GClosure is disconnected from signal).

@section create-g-closure
@code{(create-g-closure fn) @result{} closure}

@table @var
@item @var{fn}
A function that will be called by closure invokation
@item @var{closure}
A foreign pointer to allocated closure
@end table

Allocates the closure. The closure is destroyed automatically by GObject.

Example:
@example
(create-g-closure (lambda (x) (+ x 10)))
@result{}
#.(SB-SYS:INT-SAP #X006D7B20)
@end example

Example of usage from GObject binding code:
@example
(defun connect-signal (object signal handler &key after)
  (g-signal-connect-closure (ensure-object-pointer object)
                            signal
                            (create-g-closure handler)
                            after))
@end example

(TODO: GObject defines finer closure API: g_closure_ref, g_closure_unref, g_closure_invoke. It should be bound.)

@node GObject low-level
@chapter GObject low-level
@menu
* g-object-call-constructor::
* g-type-from-object::
* g-object-call-get-property::
* g-object-call-set-property::
@end menu

GObject low-level support includes facilities for working with objects as foreign pointers and using explicit function to get and set properties. This low-level support does not deal with integration of GObject with CLOS; GObject high-level support does that.

Function @code{g-type-from-object} identifies the type of the object. Function @code{g-object-call-get-property} retrieves the value of the property and function @code{g-object-call-set-property} sets the value of the property. Function @code{g-object-call-constructor} calls the constructor of the GObject type.

@node g-object-call-constructor
@section g-object-call-constructor

@code{(g-object-call-constructor object-type args-names args-values &optional args-types) @result{} object-ptr}

@table @var
@item @var{object-type}
A GType designator that specifies the object type that is to be created
@item @var{args-names}
A list of strings naming the arguments to constructor
@item @var{args-value}
A list of arguments values (in the same order as args-names)
@item @var{args-types}
Optional list of arguments types (in the same order as args-names). If not specified, it is detected automatically
@item @var{object-ptr}
A foreign pointer to newly created instance
@end table

Creates the object of type @code{object-type} by calling its constructors with arguments specified by @code{args-names}, @code{args-values}, @code{args-types}.

Example:
@example
(g-object-call-constructor "GtkButton" '("label" "use-underline") '("Hello" t) '("gchararray" "gboolean"))
@result{}
#.(SB-SYS:INT-SAP #X006D8900)

(g-object-call-get-property * "label")
@result{}
"Hello"

(g-object-call-get-property ** "use-underline")
@result{}
T
@end example

@node g-type-from-object
@section g-type-from-object

@code{(g-type-from-object object-ptr) @result{} type}

@table @var
@item @var{object-ptr}
A foreign pointer to a GObject instance
@item @var{type}
A GType designator
@end table

Returns the type of an object by a pointer to its instance

Example:
@example
(g-type-from-object (g-object-call-constructor "GtkButton" nil nil))
@result{}
"GtkButton"
@end example

@node g-object-call-get-property
@section g-object-call-get-property

@code{(g-object-call-get-property object-ptr property-name &optional property-type) @result{} property-value}

@table @var
@item @var{object-ptr}
A foreign pointer to a GObject instance
@item @var{property-name}
A string naming the property
@item @var{property-type}
Optional GType designator specifying the type of a property
@item @var{property-value}
The value of a property
@end table

Retrieves the value of a property @code{property-name} of object pointed to by @code{object-ptr}. @code{property-type} specifies the type of a property; it may be omitted.

Example:
@example
(g-object-call-constructor "GtkButton" '("label" "use-underline") '("Hello" t) '("gchararray" "gboolean"))
@result{}
#.(SB-SYS:INT-SAP #X006D8900)

(g-object-call-get-property * "label")
@result{}
"Hello"

(g-object-call-get-property ** "use-underline")
@result{}
T
@end example

@node g-object-call-set-property
@section g-object-call-set-property

@code{(g-object-call-set-property object-ptr property-name new-value &optional property-type)}

@table @var
@item @var{object-ptr}
A foreign pointer to a GObject instance
@item @var{property-name}
A string naming the property
@item @var{new-value}
A new value of a property
@item @var{property-type}
Optional GType designator specifying the type of a property
@end table

Sets the property value of property @code{property-name} of object @code{object-ptr} to @code{new-value}.

Example:
@example
(g-object-call-constructor "GtkButton" nil nil)
@result{}
#.(SB-SYS:INT-SAP #X006D8B40)

(g-object-call-set-property * "label" "Hello")
@result{}
; No value

(g-object-call-get-property ** "label")
@result{}
"Hello"
@end example

@node GObject high-level
@chapter GObject high-level
@menu
* GObject metaclass::
* Using objects::
* Signals::
* GObject foreign class::
@end menu

GObject high-level support includes integration of GObject and CLOS systems. This enables to use GObjects classes as CLOS classes (with support from @code{gobject-class} metaclass):
@itemize
@item objects are created with @code{make-instance}
@item properties are used as regular slots
@end itemize

GObjects are reference counted, and CL-GTK2-GOBJECT manages its own reference to GObjects. This enables to have transparent garbage collection of unreferenced GObjects.

To be able to use particular GObject class with CLOS, it should be defined and registered. This is accomplished by @code{defclass}'ing it with @code{gobject-class} metaclass. After GObject class is defined, it may be used as CLOS class.

Example GObject class of definition:
@example
(defclass dialog (gtk-window atk-implementor-iface buildable)
  ((has-separator :accessor dialog-has-separator
                  :initarg :has-separator
                  :allocation :gobject-property
                  :g-property-type "gboolean"
                  :g-property-name "has-separator"))
  (:metaclass gobject-class)
  (:g-type-name . "GtkDialog")
  (:g-type-initializer . "gtk_dialog_get_type"))
@end example

This example defines the CLOS class @code{dialog} that corresponds to GObject class @code{GtkDialog}. Whenever object of GObject type @code{GtkDialog} are to be received from foreign functions or passed to foreign functions, it will be mapped to CLOS class @code{dialog}. Properties that have @code{:allocation} of @code{:gobject-property} are mapped to GObject properties, and reading or writing this slot reads or writes corresponding GObject class property.

GObject does not expose objects methods. Because of this, methods are not automatically mapped to CLOS generic functions and methods. Methods should be manually wrapped with CFFI as foreign functions. Foreign type @code{g-object} aids in it. This type automatically wraps (and unwraps) the GObject class instances and handles the reference counting.

GObject high-level support enables connect signals to signal handlers. Any function may be connected as a signal handler, and GObject will release the reference on signal handler whenever it become unneded (e.g., when object is destroyed or handler is disconnected).

@node GObject metaclass
@section GObject metaclass

See MOP for information what metaclass is and why is it useful.

GObject metaclass @code{gobject-class} bridges two object systems: GObject and CLOS.

Classes that correspond to GObject classes are instances of this class.

Defining the class with metaclass @code{gobject-class} registers the type @code{:g-type-name} for conversions using GValue and CFFI foreign type @code{g-object}.

This class has the following slots:
@itemize
@item @var{g-type-name} (accessor @code{gobject-class-g-type-name}, initarg @code{:g-type-name})

Specifies the name of GObject class
@item @var{g-type-initializer} (accessor @code{gobject-class-g-type-initializer}, initarg @code{:g-type-initializer})

Name of type initializer function. This function initializes the class and returns its GType. Typically it is named @code{class_get_type}.
@item @var{interface-p} (accessor @code{gobject-class-interface-p}, initarg @code{:interface-p})

A boolean specifying whether this CLOS class corresponds to GInterface.
@end itemize

This metaclass defines the GObject classes.

Slots which have @code{:allocation} of @code{:gobject-property} are mapped to GObject properties. Such slots have following attributes:
@itemize
@item @var{:g-property-type}

A string naming GType of property
@item @var{:g-property-name}

A name of a property
@end itemize

Slots which have @code{:allocation} of @code{:gobject-fn} are mapped to a pair of accessor functions (usually named @code{class_get_property} and @code{class_set_property}). This is included because some properties are not exposed as GObject properties. Such slots have following attributes:
@itemize
@item @var{:g-property-type}
A CFFI foreign type of property
@item @var{:g-getter}
A string naming foreign getter function of a property or a symbol designating Lisp getter function. Foreign getter function should have signature @code{type class_get_property(object *)}. Lisp function should be of type @code{(function (class) type)}.
@item @var{:g-setter}
A string naming foreign setter function of a property or a symbol designating Lisp setter function. Foreign setter function should have signature @code{void class_set_property(object *, type)}. Lisp function should be of type @code{(function (class type))}.
@end itemize

Initargs of a slot are used to construct the GObject class.

Example:
@example
(defclass container (widget atk-implementor-iface buildable)
    ((border-width :allocation :gobject-property
                   :g-property-type "guint"
                   :accessor container-border-width
                   :initarg :border-width
                   :g-property-name "border-width")
     (resize-mode :allocation :gobject-property
                  :g-property-type "GtkResizeMode"
                  :accessor container-resize-mode
                  :initarg :resize-mode
                  :g-property-name "resize-mode")
     (child :allocation :gobject-property
            :g-property-type "GtkWidget"
            :accessor container-child
            :initarg :child
            :g-property-name "child")
     (focus-child :allocation :gobject-fn
                  :g-property-type g-object
                  :accessor container-focus-child
                  :initarg :focus-child
                  :g-getter "gtk_container_get_focus_child"
                  :g-setter "gtk_container_set_focus_child")
     (focus-vadjustment :allocation :gobject-fn
                        :g-property-type (g-object adjustment)
                        :accessor container-focus-vadjustment
                        :initarg :focus-vadjustment
                        :g-getter "gtk_container_get_focus_vadjustment"
                        :g-setter "gtk_container_set_focus_vadjustment")
     (focus-hadjustment :allocation :gobject-fn
                        :g-property-type (g-object adjustment)
                        :accessor container-focus-hadjustment
                        :initarg :focus-hadjustment
                        :g-getter "gtk_container_get_focus_hadjustment"
                        :g-setter "gtk_container_set_focus_hadjustment"))
    (:metaclass gobject-class)
    (:g-type-name . "GtkContainer")
    (:g-type-initializer . "gtk_container_get_type"))
@end example
(note the dot in @code{(:g-type-name . "GtkContainer")} and in @code{(:g-type-initializer . "gtk_container_get_type")}. It should be present)

@node Using objects
@section Using objects
Instances are created with @code{make-instance}. If initargs of GObject properties are supplied, they are passed to constructor. Some slots (properties) may only be set at construction time (e.g., @code{type} property of @code{GtkWindow}). Properties may be accessed (read or assigned) with defined @code{:accessor}, @code{:reader} or @code{:writer} functions.

Example:
@example
(make-instance 'gtk:dialog :has-separator t)
@result{}
#<GTK:DIALOG @{10036C5A71@}>

(defvar *d* (make-instance 'gtk:dialog :has-separator t))
@result{}
*D*

(gtk:dialog-has-separator *d*)
@result{}
T

(setf (gtk:dialog-has-separator *d*) nil)
@result{}
NIL

(gtk:dialog-has-separator *d*)
@result{}
NIL
@end example

@node Signals
@section Signals

To connect handler to a signal, @code{connect-signal} function is used.

@code{(connect-signal object signal handler &key after)}

@table @var
@item @var{object}
An instance of GObject object
@item @var{signal}
A signal name
@item @var{handler}
A function
@item @var{after}
A boolean specifying whether the handler should be called after the default handler
@end table

Connects the @code{handler} to signal @code{signal} on object @code{object}. Signature of @code{handler} should comply with signature of a signal. @code{handler} will be called with arguments of type specified by signal with the object (on which the signal was emitted) prepended to them and it should return the value of the signal's return type.

Example:
@example
(defvar *d* (make-instance 'gtk:dialog))
@result{}
*D*

*d*
@result{}
#<GTK:DIALOG @{1002D866F1@}>

(parse-signal-name "GtkDialog" "response")
@result{}
#<Signal [#86] void GtkDialog.response(gint) [RUN-LAST]>

(connect-signal *d* "response" (lambda (dialog response-value) (print dialog) (print response-value)))

(emit-signal *d* "response" 14)
@result{}
;; Prints:
#<GTK:DIALOG @{1002D866F1@}>
14 
@end example

Function @code{emit-signal} is used to emit signals on objects.

@code{(emit-signal object signal-name &rest args) @result{} return-value}

@table @var
@item @var{object}
An object on which the signal should be emitted
@item @var{signal-name}
A string naming the signal
@item @var{args}
Arguments for a signal
@item @var{return-value}
Return value of a signal
@end table

Emits the signal and calls all handlers of the signal. If signal returns a value, it is returned from @code{emit-signal}.

Example:
@example
(defvar *d* (make-instance 'gtk:dialog))
@result{}
*D*

*d*
@result{}
#<GTK:DIALOG @{1002D866F1@}>

(parse-signal-name "GtkDialog" "response")
@result{}
#<Signal [#86] void GtkDialog.response(gint) [RUN-LAST]>

(connect-signal *d* "response" (lambda (dialog response-value) (print dialog) (print response-value)))

(emit-signal *d* "response" 14)
@result{}
;; Prints:
#<GTK:DIALOG @{1002D866F1@}>
14 
@end example

@node GObject foreign class
@section GObject foreign class

To enable passing GObject instance between Lisp code and foreign code, @code{g-object} foreign type is introduced.

This type has the following syntax:
@code{(g-object &optional type)} or @code{g-object}.

When the @code{g-object} foreign type is specified as a return type of a function, the value is converted to instance of corresponding CLOS class. If @code{type} is specified then it is checked that object is of this type.

When the @code{g-object} foreign type is specified as a type of function's argument, the value is converted to pointer to GObject. If @code{type} is specified then it is checked that the object is of this type.

This defines the function that may be called with instances of types @code{container} and @code{widget}:
@example
(defcfun (container-add "gtk_container_add") :void
  (container (g-object container))
  (widget (g-object widget)))

(let ((window (make-instance 'gtk-window))
      (widget (make-instance 'button)))
  (container-add window widget))
@end example
(@code{gtk-window} is a subclass of @code{container}; @code{button} is a subclass of @code{widget})

This defines the function that returns an instance of GObject class:
@example
(defcfun (bin-child "gtk_bin_get_child") (g-object widget)
  (bin (g-object bin)))

(let ((window (make-instance 'gtk-window))
      (widget (make-instance 'button)))
  (container-add window widget)
  (bin-child window))
@result{}
#<GTK:BUTTON @{1002DE74B1@}>
@end example

@node Subclassing GObjects and implementing GInterfaces
@chapter Subclassing GObjects and implementing GInterfaces

@node GBoxed
@chapter GBoxed
@menu
* define-g-boxed-class::
* define-g-boxed-ref::
@end menu

GObject manual defines this type in the following way:

``GBoxed is a generic wrapper mechanism for arbitrary C structures. The only thing the type system needs to know about the structures is how to copy and free them, beyond that they are treated as opaque chunks of memory.

Boxed types are useful for simple value-holder structures like rectangles or points. They can also be used for wrapping structures defined in non-GObject based libraries.''

Naturally, it is quite hard to provide support for such structures. At the moment, support for GBoxed is pretty bad.

Basically, two use cases of GBoxed structures are provided:
@itemize
@item structure is mapped to Lisp structure defined with @code{defstruct}. This is complex scenario and it supports inheritance between structure. Its main use is to define the @code{GdkEvent} structure wrapper. Macro @code{define-g-boxed-class} supports this use case.
@item structure is mapped to Lisp wrapper that contains pointer to structure and provides accessor functions (by calling foreign function or calling Lisp function). Macro @code{define-g-boxed-ref} supports this use case.
@end itemize

In both scenarios, foreign functions and GValue type registrations are provided that provide wrapping and unwrapping behaivour (it yet remains to be proven that the behaviour is correct in all cases with regard to issues of memory management, ownership, lifetime). In both cases it is possible to pass the structure by reference, allowing the foreign function (or the callback code) to change the contents of GBoxed.

It is expected that the support for GBoxed structures will be improved.

@node define-g-boxed-class
@section define-g-boxed-class

@example
(define-g-boxed-class g-name-and-c-name name (&optional superclass-and-dispatch (export t))
  &body slot*)

g-name-and-c-name ::= nil
g-name-and-c-name ::= (g-name c-name)
superclass-and-dispatch ::= (&optional superclass dispatch-slot dispatch-values)
slot ::= slot-name slot-type &key initform parser unparser
@end example

@table @var
@item @var{g-name}
A string naming the type of this GBoxed; for inherited classes, it should be @code{NIL}
@item @var{c-name}
A symbol naming the generated CFFI foreign structure definition corresponding to this GBoxed. This name should not conflict with other CFFI types.
@item @var{name}
A symbol naming the Lisp structure that will be generated
@item @var{superclass}
A symbol naming the structure defined with @code{define-g-boxed-class} that is the superclass of this structure
@item @var{dispatch-slot}
A slot of the superclass structure that identifies the specific type of structure (``discriminator'')
@item @var{dispatch-values}
A value or a list of values of the @code{dispatch-slot} that correspond to this GBoxed class
@item @var{slot-name}
Name of a slot
@item @var{slot-type}
CFFI foreign type of a slot
@item @var{initform}
An optional initform for @code{defstruct} slot
@item @var{parser}
An optional parser function designator for slot. Parser function is called to get the value for slot when the GBoxed is passed to Lisp with the following arguments: @code{(name pointer)} where the @code{name} is the name of a structure being defined and the @code{pointer} is a foreign pointer to the C structure.
@item @var{unparser}
An optional unparser function designator for a slot. Unparser function is called to write the slot value to GBoxed structure. It is called with arguments @code{(name pointer object)} where @code{name} is the name of a structure being defined, @code{pointer} is the pointer to the C structure and the @code{object} is object whose slot value should be written to structure.
@end table

Defines the @code{defstruct} wrapper for GBoxed type. Various parameters control how the structure is converted between C and Lisp representations.

@code{define-g-boxed-class} supports basic single inheritance. This is provided to support ``generic'' C structures like @code{GdkEvent} that contain a ``type'' field and a @code{union} of other substructures. The natural mapping of such structure to Lisp is not one, but several structures that are inherited one from another. This supports e.g. method dispatching on @code{GdkEvent} types (if it is ever necessary).

The only use of @code{define-g-boxed-class} that involves inheritance is the @code{GdkEvent} structure. It is defined as follows.
@example
(define-g-boxed-class ("GdkEvent" event-struct) event ()
  (type event-type)
  (window (g-object gdk-window))
  (send-event (:boolean :int8)))

(define-g-boxed-class nil event-key ((event type (:key-press :key-release)))
  (time :uint32)
  (state modifier-type)
  (keyval :uint)
  (length :int)
  (string (:string :free-from-foreign nil :free-to-foreign nil))
  (hardware-keycode :uint16)
  (group :uint8)
  (is-modifier :uint))

(define-g-boxed-class nil event-button ((event type (:button-press :2button-press :3button-press :button-release)))
  (time :uint32)
  (x :double)
  (y :double)
  (axes (fixed-array :double 2))
  (state :uint)
  (button :uint)
  (device (g-object device))
  (x-root :double)
  (y-root :double))
@end example

Some simpler uses include following examples:
@example
(define-g-boxed-class "GdkFont" font ()
  (type font-type :initform :font)
  (ascent :int :initform 0)
  (descent :int :initform 0))

(define-g-boxed-class "GdkColor" color ()
  (pixel :uint32 :initform 0)
  (red :uint16 :initform 0)
  (green :uint16 :initform 0)
  (blue :uint16 :initform 0))

(define-g-boxed-class "GdkGeometry" geometry ()
  (min-width :int :initform 0)
  (min-height :int :initform 0)
  (max-width :int :initform 0)
  (max-height :int :initform 0)
  (base-width :int :initform 0)
  (base-height :int :initform 0)
  (width-increment :int :initform 0)
  (height-increment :int :initform 0)
  (min-aspect :double :initform 0.0d0)
  (max-aspect :double :initform 0.0d0)
  (gravity gravity :initform :north-west))
@end example

@node define-g-boxed-ref
@section define-g-boxed-ref

@code{g-boxed-ref} class is defined:
@example
(defclass g-boxed-ref ()
  ((pointer :accessor pointer :initarg :pointer)))
@end example

This class holds the pointer to structure. GBoxed-ref types are subclasses of this class.

@example
(define-g-boxed-ref g-name name
  &rest property*)

property ::= (:free-function free-function)
property ::= (:alloc-function alloc-function)
property ::= (:slots &rest slot*)
slot ::= (slot-name &key reader writer type (accessor slot-name))
@end example

@table @var
@item @var{g-name}
A string that names the GBoxed type
@item @var{name}
A symbol that is the name for generated class
@item @var{free-function}
Mandatory designator for a function that frees the allocated object. This function accepts a single argument - CFFI foreign pointer.
@item @var{alloc-function}
Mandatory designator for a function that allocates the object. This function accepts zero arguments and returns CFFI foreign pointer to fresh object.
@item @var{slot-name}
A symbol naming the slot
@item @var{type}
A CFFI foreign type of a slot
@item @var{reader}
@code{NIL} or a string or a function designator. If it is @code{NIL} the the slot is not readable. If it is a string then it names the C function that accepts the pointer to structure and returns the value of a slot of specified CFFI type. If it is a function designator that it designates a function that accepts the Lisp object and returns its slot value.
@item @var{writer}
@code{NIL} or string or a function designator. If it is a @code{NIL} then the slot is not writable. If it is a string then it names the C function that accepts the pointer to C structure and a value (of specified CFFI type) and assigns it to the slot of a structure. If it is a function designator then it specifies a function that accepts the new slot value and a Lisp object and assigns it to the slot.
@item @var{accessor}
A symbol namin the accessor function for slot.
@end table

Defines a class corresponding to GBoxed type that is passed by reference (e.g., @code{GtkTextIter}). Class is made a subclass of @code{g-boxed-ref}.

The memory occupied by this class is managed automatically: after the GC collects the Lisp instance, @code{free-function} is used to free the structure.

Example:
@example
(defcstruct tree-iter
  (stamp :int)
  (user-data :pointer)
  (user-data-2 :pointer)
  (user-data-3 :pointer))

(defun tree-iter-get-stamp (i) (foreign-slot-value (pointer i) 'tree-iter 'stamp))
(defun tree-iter-set-stamp (value i) (setf (foreign-slot-value (pointer i) 'tree-iter 'stamp) value))
(defun tree-iter-get-user-data (i) (pointer-address (foreign-slot-value (pointer i) 'tree-iter 'user-data)))
(defun tree-iter-set-user-data (value i) (setf (foreign-slot-value (pointer i) 'tree-iter 'user-data) (make-pointer value)))

(defun tree-iter-alloc () (glib:g-malloc (foreign-type-size 'tree-iter)))
(defun tree-iter-free (v) (glib:g-free v))

(define-g-boxed-ref "GtkTreeIter" tree-iter
  (:slots (stamp :reader tree-iter-get-stamp :writer tree-iter-set-stamp :accessor tree-iter-stamp)
          (user-data :reader tree-iter-get-user-data :writer tree-iter-set-user-data :accessor tree-iter-user-data))
  (:alloc-function tree-iter-alloc)
  (:free-function tree-iter-free))
@end example

Another example:
@example
(define-foreign-type unichar ()
  ()
  (:actual-type :uint32)
  (:simple-parser unichar))

(defmethod translate-from-foreign (value (type unichar))
  (code-char value))

(defmethod translate-to-foreign (value (type unichar))
  (char-code value))

(define-g-boxed-ref "GtkTextIter" text-iter
  (:free-function gtk-text-iter-free)
  (:alloc-function gtk-text-iter-alloc)
  (:slots (text-iter-buffer :reader "gtk_text_iter_get_buffer" :type (g-object text-buffer))
          (text-iter-offset :reader "gtk_text_iter_get_offset" :writer "gtk_text_iter_set_offset" :type :int)
          (text-iter-line :reader "gtk_text_iter_get_line" :writer "gtk_text_iter_set_line" :type :int)
          (text-iter-line-offset :reader "gtk_text_iter_get_line_offset" :writer "gtk_text_iter_set_line_offset" :type :int)
          (text-iter-visible-line-offset :reader "gtk_text_iter_get_visible_line_offset" :writer "gtk_text_iter_set_visible_line_offset" :type :int)
          (text-iter-char :reader "gtk_text_iter_get_char" :type unichar)
          (text-iter-pixbuf :reader "gtk_text_iter_get_pixbuf" :type (g-object pixbuf))
          (text-iter-marks :reader "gtk_text_iter_get_marks" :type (gslist (g-object text-mark) :free-from-foreign t))
          (text-iter-child-anchor :reader "gtk_text_iter_get_child_anchor" :type (g-object text-child-anchor))
          (text-iter-tags :reader "gtk_text_iter_get_tags" :type (gslist (g-object text-tag) :free-from-foreign t))
          (text-iter-chars-in-line :reader "gtk_text_iter_get_chars_in_line" :type :int)
          (text-iter-language :reader "gtk_text_iter_get_language" :type :pointer)
          (text-iter-is-end :reader "gtk_text_iter_is_end" :type :boolean)
          (text-iter-is-start :reader "gtk_text_iter_is_start" :type :boolean)
          (text-iter-can-insert :reader "gtk_text_iter_can_insert" :type :boolean)
          (text-iter-starts-word :reader "gtk_text_iter_starts_word" :type :boolean)
          (text-iter-ends-word :reader "gtk_text_iter_ends_word" :type :boolean)
          (text-iter-inside-word :reader "gtk_text_iter_inside_word" :type :boolean)
          (text-iter-starts-line :reader "gtk_text_iter_starts_line" :type :boolean)
          (text-iter-ends-line :reader "gtk_text_iter_ends_line" :type :boolean)
          (text-iter-starts-sentence :reader "gtk_text_iter_starts_sentence" :type :boolean)
          (text-iter-ends-sentence :reader "gtk_text_iter_ends_sentence" :type :boolean)
          (text-iter-inside-sentence :reader "gtk_text_iter_inside_sentence" :type :boolean)
          (text-iter-is-cursor-position :reader "gtk_text_iter_is_cursor_position" :type :boolean)))

(defcstruct %text-iter
  (dummy1 :pointer)
  (dummy2 :pointer)
  (dummy3 :int)
  (dummy4 :int)
  (dummy5 :int)
  (dummy6 :int)
  (dummy7 :int)
  (dummy8 :int)
  (dummy9 :pointer)
  (dummy10 :pointer)
  (dummy11 :int)
  (dummy12 :int)
  (dummy13 :int)
  (dummy14 :pointer))

(defcfun gtk-text-iter-copy :pointer
  (iter :pointer))

(defcfun gtk-text-iter-free :void
  (iter :pointer))

(defun gtk-text-iter-alloc ()
  (with-foreign-object (iter '%text-iter)
    (gtk-text-iter-copy iter)))
@end example

@node Generating type definitions by introspection
@chapter Generating type definitions by introspection
@menu
* define-g-object-class::
* define-g-interface::
* define-g-enum::
* define-g-flags::
* get-g-enum-definition::
* get-g-flags-definition::
* get-g-interface-definition::
* get-g-class-definition::
* Specifying additional properties for CLOS classes::
* Generating names for CLOS classes and accessors::
* generate-types-hierarchy-to-file::
@end menu

CL-GTK2-GOBJECT includes facilities for automatically generating parts of bindings for libraries that use GObject type system.

@node define-g-object-class
@section define-g-object-class

@example
(define-g-object-class g-type-name name
  (&key (superclass 'g-object) (export t) interfaces type-initializer)
  (&rest property*))

property ::= (name accessor gname type readable writable)
property ::= (:cffi name acessor type reader writer)
@end example

Parameters of @code{define-g-object-class}
@table @var
@item @var{superclass}
A symbol naming the superclass of this class
@item @var{export}
Whether to export the name of the class and names of autogenerated properties names from the current package.
@item @var{interfaces}
A list of interfaces the this class implements
@item @var{type-initializer}
A string naming the type initiliazer function. It is usually named @code{class_get_type}.
@item @var{properties}
A list of slots of a class
@end table

Parameters of @code{property}:
@table @var
@item @var{name}
A symbol naming the slot
@item @var{accessor}
A symbol naming the accessor function for this slot
@item @var{gname}
A string naming the property of GObject
@item @var{type}
A string naming the type of property of GObject (for GObject properties); or a symbol naming CFFI foreign type (for slots mapped to foreign accessors)
@item @var{readable}
A boolean specifying whether the slot can be read
@item @var{writable}
A boolean specifying whether the slot can be assigned to
@item @var{reader}
A string or a symbol naming getter function. See description of @code{gobject-class} metaclass for information.
@item @var{writter}
A string or a symbol naming setter function. See description of @code{gobject-class} metaclass for information.
@end table

Macro that expands to @code{defclass} for specified class. Additionally, if @code{export} is true, it exports accessor names and name of a class.

Example:
@example
(define-g-object-class "GtkContainer" container
  (:superclass widget :export t :interfaces
               ("AtkImplementorIface" "GtkBuildable")
               :type-initializer "gtk_container_get_type")
  ((border-width container-border-width "border-width" "guint" t t)
   (resize-mode container-resize-mode "resize-mode" "GtkResizeMode" t t)
   (child container-child "child" "GtkWidget" nil t)
   (:cffi focus-child container-focus-child g-object "gtk_container_get_focus_child" "gtk_container_set_focus_child")
   (:cffi focus-vadjustment container-focus-vadjustment (g-object adjustment) "gtk_container_get_focus_vadjustment" "gtk_container_set_focus_vadjustment")
   (:cffi focus-hadjustment container-focus-hadjustment (g-object adjustment) "gtk_container_get_focus_hadjustment" "gtk_container_set_focus_hadjustment")))
@end example

@node define-g-interface
@section define-g-interface

@example
(define-g-interface g-type-name name (&key (export t) type-initializer)
  &body property*)

property ::= (name accessor gname type readable writable)
property ::= (:cffi name acessor type reader writer)
@end example

Parameters of @code{define-g-interface}
@table @var
@item @var{export}
Whether to export the name of the interface and names of autogenerated properties names from the current package.
@item @var{type-initializer}
A string naming the type initiliazer function. It is usually named @code{interface_get_type}.
@item @var{properties}
A list of slots of a interface
@end table

Parameters of @code{property}:
@table @var
@item @var{name}
A symbol naming the slot
@item @var{accessor}
A symbol naming the accessor function for this slot
@item @var{gname}
A string naming the property of GObject
@item @var{type}
A string naming the type of property of GObject (for GObject properties); or a symbol naming CFFI foreign type (for slots mapped to foreign accessors)
@item @var{readable}
A boolean specifying whether the slot can be read
@item @var{writable}
A boolean specifying whether the slot can be assigned to
@item @var{reader}
A string or a symbol naming getter function. See description of @code{gobject-class} metaclass for information.
@item @var{writter}
A string or a symbol naming setter function. See description of @code{gobject-class} metaclass for information.
@end table

Macro that expands to @code{defclass} for specified interface. Additionally, if @code{export} is true, it exports accessor names and name of a interface.

Example:
@example
(define-g-interface "GtkFileChooser" file-chooser
  (:export t :type-initializer "gtk_file_chooser_get_type")
  (do-overwrite-confirmation file-chooser-do-overwrite-confirmation "do-overwrite-confirmation" "gboolean" t t)
  (select-multiple file-chooser-select-multiple "select-multiple" "gboolean" t t)
  (filter file-chooser-filter "filter" "GtkFileFilter" t t)
  (local-only file-chooser-local-only "local-only" "gboolean" t t)
  (preview-widget file-chooser-preview-widget "preview-widget" "GtkWidget" t t)
  (use-preview-label file-chooser-use-preview-label "use-preview-label" "gboolean" t t)
  (preview-widget-active file-chooser-preview-widget-active "preview-widget-active" "gboolean" t t)
  (file-system-backend file-chooser-file-system-backend "file-system-backend" "gchararray" nil nil)
  (extra-widget file-chooser-extra-widget "extra-widget" "GtkWidget" t t)
  (show-hidden file-chooser-show-hidden "show-hidden" "gboolean" t t)
  (action file-chooser-action "action" "GtkFileChooserAction" t t)
  (:cffi current-name file-chooser-current-name
   (:string :free-to-foreign t :encoding :utf-8) nil "gtk_file_chooser_set_current_name")
  (:cffi filename file-chooser-filename
   (g-string :free-from-foreign t :free-to-foreign t)
   "gtk_file_chooser_get_filename" "gtk_file_chooser_set_filename")
  (:cffi current-folder file-chooser-current-folder
   (g-string :free-from-foreign t :free-to-foreign t)
   "gtk_file_chooser_get_current_folder"
   "gtk_file_chooser_set_current_folder")
  (:cffi uri file-chooser-uri
   (g-string :free-from-foreign t :free-to-foreign t)
   "gtk_file_chooser_get_uri" "gtk_file_chooser_set_uri")
  (:cffi current-folder-uri file-chooser-current-folder-uri
   (g-string :free-from-foreign t :free-to-foreign t)
   "gtk_file_chooser_get_current_folder_uri"
   "gtk_file_chooser_set_current_folder_uri")
  (:cffi preview-filename file-chooser-preview-filename
   (g-string :free-from-foreign t :free-to-foreign t)
   "gtk_file_chooser_get_preview_filename" nil)
  (:cffi preview-uri file-chooser-preview-uri
   (g-string :free-from-foreign t :free-to-foreign t)
   "gtk_file_chooser_get_preview_uri" nil))
@end example

@node define-g-enum
@section define-g-enum

@example
(define-g-enum g-name name (&key (export t) type-initializer) &body value*)

value ::= :keyword
value ::= (:keyword integer)
@end example

@table @var
@item @var{g-name}
A string naming the GEnum type
@item @var{name}
A symbol naming the CFFI enumeration type
@item @var{export}
A boolean indicating whether to export @code{name}
@item @var{type-initializer}
A string naming the foreign type initializer function. Usually named @code{enum_get_type}.
@end table

Macro that defines CFFI enumeration, registers it with GValue, and calls the type initializer.

Example:
@example
(define-g-enum "GtkTextDirection" text-direction
  (:export t :type-initializer "gtk_text_direction_get_type")
  (:none 0) (:ltr 1) (:rtl 2))

(define-g-enum "GtkSizeGroupMode" size-group-mode
 (:export t :type-initializer "gtk_size_group_mode_get_type")
 :none :horizontal :vertical :both)
@end example

@node define-g-flags
@section define-g-flags

@example
(define-g-flags g-name name (&key (export t) type-initializer) &body value*)

value ::= :keyword
value ::= (:keyword integer)
@end example

@table @var
@item @var{g-name}
A string naming the GFlags type
@item @var{name}
A symbol naming the CFFI flags type
@item @var{export}
A boolean indicating whether to export @code{name}
@item @var{type-initializer}
A string naming the foreign type initializer function. Usually named @code{flags_get_type}.
@end table

Macro that defines CFFI bitfield, registers it with GValue, and calls the type initializer.

Example:
@example
(define-g-flags "GtkAttachOptions" attach-options
  (:export t :type-initializer "gtk_attach_options_get_type")
  (:expand 1) (:shrink 2) (:fill 4))

(define-g-flags "GtkButtonAction" button-action
  (:export t :type-initializer "gtk_button_action_get_type")
  :ignored :selects :drags :expands)
@end example

@node get-g-enum-definition
@section get-g-enum-definition

@code{(get-g-enum-definition type &optional lisp-name-package) @result{} definition}

@table @var
@item @var{type}
A string naming the GEnum type
@item @var{lisp-name-package}
A package that will be used as a package for generated symbols (enum name). If not specified, symbols are interned in @code{*package*}
@item @var{definition}
A Lisp form that when evaluated defines the GEnum.
@end table

Uses GObject introspection capabilities to automatically produce the definition of GEnum. The foreign library that defines the enum type should be loaded.

See @ref{Generating names for CLOS classes and accessors} for information about used method for generating names.

Example:
@example
(get-g-enum-definition "GtkDirectionType")
@result{}
(DEFINE-G-ENUM "GtkDirectionType" GTK-DIRECTION-TYPE
               (:EXPORT T :TYPE-INITIALIZER "gtk_direction_type_get_type")
               (:TAB-FORWARD 0) (:TAB-BACKWARD 1) (:UP 2) (:DOWN 3) (:LEFT 4)
               (:RIGHT 5))
@end example

@node get-g-flags-definition
@section get-g-flags-definition

@code{(get-g-flags-definition type &optional lisp-name-package) @result{} definition}

@table @var
@item @var{type}
A string naming the GFlags type
@item @var{lisp-name-package}
A package that will be used as a package for generated symbols (flags name). If not specified, symbols are interned in @code{*package*}
@item @var{definition}
A Lisp form that when evaluated defines the GFlags.
@end table

Uses GObject introspection capabilities to automatically produce the definition of GFlags. The foreign library that defines the flags type should be loaded.

See @ref{Generating names for CLOS classes and accessors} for information about used method for generating names.

Example:
@example
(get-g-flags-definition "GtkCalendarDisplayOptions")
@result{}
(DEFINE-G-FLAGS "GtkCalendarDisplayOptions" GTK-CALENDAR-DISPLAY-OPTIONS
                (:EXPORT T :TYPE-INITIALIZER
                 "gtk_calendar_display_options_get_type")
                (:SHOW-HEADING 1) (:SHOW-DAY-NAMES 2) (:NO-MONTH-CHANGE 4)
                (:SHOW-WEEK-NUMBERS 8) (:WEEK-START-MONDAY 16)
                (:SHOW-DETAILS 32))
@end example

@node get-g-interface-definition
@section get-g-interface-definition

@code{get-g-interface-definition type &optional lisp-name-package) @result{} definition}

@table @var
@item @var{type}
A string naming the GInterface type
@item @var{lisp-name-package}
A package that will be used as a package for generated symbols (type name, accessor names). If not specified, symbols are interned in @code{*package*}
@item @var{definition}
A Lisp form that when evaluated defines the GInterface.
@end table

Uses GObject introspection capabilities to automatically produce the definition of GInterface. The foreign library that defines the GInterface type should be loaded.

See @ref{Generating names for CLOS classes and accessors} for information about used method for generating names.

Example:
@example
(get-g-interface-definition "GtkActivatable")
@result{}
(DEFINE-G-INTERFACE "GtkActivatable" GTK-ACTIVATABLE
                    (:EXPORT T :TYPE-INITIALIZER "gtk_activatable_get_type")
                    (USE-ACTION-APPEARANCE
                     GTK-ACTIVATABLE-USE-ACTION-APPEARANCE
                     "use-action-appearance" "gboolean" T T)
                    (RELATED-ACTION GTK-ACTIVATABLE-RELATED-ACTION
                     "related-action" "GtkAction" T T))
@end example

@node get-g-class-definition
@section get-g-class-definition


@code{get-g-class-definition type &optional lisp-name-package) @result{} definition}

@table @var
@item @var{type}
A string naming the GObject type
@item @var{lisp-name-package}
A package that will be used as a package for generated symbols (type name, accessor names). If not specified, symbols are interned in @code{*package*}
@item @var{definition}
A Lisp form that when evaluated defines the GObject.
@end table

Uses GObject introspection capabilities to automatically produce the definition of GClass. The foreign library that defines the GObject type should be loaded.

See @ref{Generating names for CLOS classes and accessors} for information about used method for generating names.

Example:
@example
(get-g-class-definition "GtkButton")
@result{}
(DEFINE-G-OBJECT-CLASS "GtkButton" GTK-BUTTON
                       (:SUPERCLASS GTK-BIN :EXPORT T :INTERFACES
                        ("AtkImplementorIface" "GtkActivatable" "GtkBuildable")
                        :TYPE-INITIALIZER "gtk_button_get_type")
                       ((LABEL GTK-BUTTON-LABEL "label" "gchararray" T T)
                        (IMAGE GTK-BUTTON-IMAGE "image" "GtkWidget" T T)
                        (RELIEF GTK-BUTTON-RELIEF "relief" "GtkReliefStyle" T
                         T)
                        (USE-UNDERLINE GTK-BUTTON-USE-UNDERLINE "use-underline"
                         "gboolean" T T)
                        (USE-STOCK GTK-BUTTON-USE-STOCK "use-stock" "gboolean"
                         T T)
                        (FOCUS-ON-CLICK GTK-BUTTON-FOCUS-ON-CLICK
                         "focus-on-click" "gboolean" T T)
                        (XALIGN GTK-BUTTON-XALIGN "xalign" "gfloat" T T)
                        (YALIGN GTK-BUTTON-YALIGN "yalign" "gfloat" T T)
                        (IMAGE-POSITION GTK-BUTTON-IMAGE-POSITION
                         "image-position" "GtkPositionType" T T)))
@end example

@node Specifying additional properties for CLOS classes
@section Specifying additional properties for CLOS classes

Some properties are not exposed through GObject introspection facilities, but are rather present as a pair of functions (@code{class_get_property}, @code{class_set_property}). @code{gobject-class} metaclass supports such properties. For these properties to be included in automatically generated class definitions, they should be made known to the generator.

Definitions generator uses variable @code{*additional-properties*} to get this information.

Variable @code{*additional-properties*} contains a plist that maps GType names to a list of properties definitions (See @ref{define-g-object-class} for syntax of properties definitions).

To supply the bindings generator with this information, bind @code{*additional-properties*} to such list when the generator is run.

Example:
@example
(("GtkTreeViewColumn"
  (:cffi gtk::tree-view
         gtk::tree-view-column-tree-view
         g-object "gtk_tree_view_column_get_tree_view" nil)
  (:cffi gtk::sort-column-id
         gtk::tree-view-column-sort-column-id
         :int "gtk_tree_view_column_get_sort_column_id" "gtk_tree_view_column_set_sort_column_id")
  (:cffi gtk::cell-renderers
         gtk::tree-view-column-cell-renderers
         (glist g-object  :free-from-foreign t) "gtk_tree_view_column_get_cell_renderers" nil))
 ("GtkTreeSelection"
  (:cffi gtk::mode
         gtk::tree-selection-mode
         gtk::selection-mode "gtk_tree_selection_get_mode" "gtk_tree_selection_set_mode")
  (:cffi gtk::select-function
         gtk::tree-selection-select-function
         nil gtk::tree-selection-get-selection-function gtk::tree-selection-set-select-function)))
@end example

@node Generating names for CLOS classes and accessors
@section Generating names for CLOS classes and accessors

Names of types are generated by mapping @code{CamelCaseNames} to @code{dash-separated-names} and interning them in specified package. Additionally, prefix from beginning of the name may be stripped (@code{"GtkWidget"} has prefix @code{"Gtk"}, after stripping it maps to @code{widget}). Some names may require special processing (e.g., @code{"GObject"}, @code{"GInitiallyUnowned"} should map to class names in @code{gobject} package; @code{"GtkWindow"} and @code{"GdkWindow"} should receive different @code{symbol-name}s so that they can both be imported in one package).

Accessors for slots are generated by concatenating class name, dash and slot name, producing names like @code{class-slot}: @code{container-child}, @code{button-label}, etc.

Name generation affected by following variables:
@itemize
@item @var{*strip-prefix*}
A string variable specifying the prefix that should to be stripped from the names to generate symbols (e.g., if @code{(equal "Gtk" *strip-prefix*)}, then type named @code{"GtkWidget"} will map to class named @code{widget}.
@item @var{*lisp-name-exceptions*}
A plist mapping from strings (type names) to symbols (class names) that have special name processing.
Example:
@example
`(("GObject" gobject:g-object)
  ("GtkObject" ,(intern "GTK-OBJECT" (find-package :gtk)))
  ("GInitiallyUnowned" gobject::g-initially-unowned)
  ("GtkWindow" ,(intern "GTK-WINDOW" (find-package :gtk)))
  ("GtkUIManager" ,(intern "UI-MANAGER" (find-package :gtk)))
  ("GtkUIManagerItemType" ,(intern "UI-MANAGER-ITEM-TYPE" (find-package :gtk))))
@end example
@end itemize

@node generate-types-hierarchy-to-file
@section generate-types-hierarchy-to-file

@example
(generate-types-hierarchy-to-file file
                                  root-type
                                  &key include-referenced
                                  prefix
                                  package
                                  exceptions
                                  prologue
                                  interfaces
                                  enums
                                  flags
                                  objects
                                  exclusions
                                  additional-properties)
@end example

@table @var
@item @var{file}
A string or pathname naming the file, or a stream.
@item @var{root-type}
A GType designator for a root type. All types that inherit from this type will be defined.
@item @var{&key include-referenced}
A boolean. Specifies whether referenced types should be included. Type is referenced if it is an interface or a type of property of type included in generation
@item @var{prefix}
A string naming the prefix that should be removed from the beginning of names
@item @var{package}
A package which will contain generated names of types, slots and accessors. It will also be the current package when the definitions are written to file
@item @var{exceptions}
A plist that maps GType names to their Lisp names.
See @ref{Generating names for CLOS classes and accessors} for more info on exceptions from name generation mechanism
@item @var{prologue}
A string that will be included verbatim in generated code file
@item @var{interfaces}
Additional list of interfaces that will also be included in generation
@item @var{enums}
Additional list of enums that will also be included in generation
@item @var{flags}
Additional list of flags that will also be included in generation
@item @var{objects}
Additional list of object types that will also be included in generation
@item @var{exclusions}
A list of GType names that will be excluded from generation
@item @var{additional-properties}
A plist of properties definitions that will be added to generated classes.
See @ref{Specifying additional properties for CLOS classes} for more information.
@end table

Generates definitions for all types in a type hierarchy. Recursively scan types hierarchy (starting from @code{root} and @code{objects} and @code{interfaces}) (except types that were specifically excluded) and generate defintion for every mentioned type. Parameters control various aspects of definition generation.

Example of usage:
@example
(generate-types-hierarchy-to-file
 "gtk.generated-classes.lisp"
 "GtkObject"
 :include-referenced t
 :prefix "Gtk"
 :package (or (find-package :gtk) (make-package :gtk))
 :exceptions `(("GObject" gobject:g-object)
               ("GtkObject" ,(intern "GTK-OBJECT" (find-package :gtk)))
               ("GInitiallyUnowned" gobject::g-initially-unowned)
               ("GtkWindow" ,(intern "GTK-WINDOW" (find-package :gtk)))
               ("GtkUIManager" ,(intern "UI-MANAGER" (find-package :gtk)))
               ("GtkUIManagerItemType" ,(intern "UI-MANAGER-ITEM-TYPE" (find-package :gtk))))
 :prologue (format nil "(in-package :gtk)")
 :interfaces '("GtkBuildable" "GtkCellEditable" ...)
 :objects '("GtkSettings" "GtkRcStyle" ...)
 :flags '("GtkTextSearchFlags" "GtkAccelFlags" ...)
 :enums '("GtkTextDirection" "GtkSizeGroupMode" ...)
 :exclusions '("PangoStretch" "PangoVariant" ...)
 :additional-properties
 '(("GtkTreeViewColumn"
    (:cffi
     gtk::tree-view
     gtk::tree-view-column-tree-view
     g-object
     "gtk_tree_view_column_get_tree_view"
     nil)
    ...)
   ...))
@end example

@bye