it still has quite a few. @xref{Contributed Modules}.
@menu
-* Garbage Collection::
-* Metaobject Protocol::
-* Support For Unix::
-* Customization Hooks for Users::
-* Tools To Help Developers::
-* Resolution of Name Conflicts::
-* Hash Table Extensions::
-* Miscellaneous Extensions::
-* Stale Extensions::
-* Efficiency Hacks::
+* Reader Extensions::
+* Package-Local Nicknames::
+* Garbage Collection::
+* Metaobject Protocol::
+* Support For Unix::
+* Customization Hooks for Users::
+* Tools To Help Developers::
+* Resolution of Name Conflicts::
+* Hash Table Extensions::
+* Random Number Generation::
+* Miscellaneous Extensions::
+* Stale Extensions::
+* Efficiency Hacks::
@end menu
+@node Reader Extensions
+@comment node-name, next, previous, up
+@section Reader Extensions
+@cindex Reader Extensions
+
+SBCL supports extended package prefix syntax, which allows specifying
+an alternate package instead of @code{*package*} for the reader to use
+as the default package for interning symbols:
+
+@lisp
+<package-name>::<form-with-interning-into-package>
+@end lisp
+
+Example:
+
+@lisp
+ 'foo::(bar quux zot) == '(foo::bar foo::quux foo::zot)
+@end lisp
+
+Doesn't alter @code{*package*}: if @code{foo::bar} would cause a
+read-time package lock violation, so does @code{foo::(bar)}.
+
+@node Package-Local Nicknames
+@comment node-name, next, previous, up
+@section Package-Local Nicknames
+@cindex Package-Local Nicknames
+
+SBCL allows giving packages local nicknames: they allow short and
+easy-to-use names to be used without fear of name conflict associated
+with normal nicknames.
+
+A local nickname is valid only when inside the package for which it
+has been specified. Different packages can use same local nickname for
+different global names, or different local nickname for same global
+name.
+
+Symbol @code{:package-local-nicknames} in @code{*features*} denotes the
+support for this feature.
+
+@findex @cl{defpackage}
+@defmac @cl{defpackage} name [[option]]* @result{} package
+
+Options are extended to include
+
+@itemize
+@item
+@code{:local-nicknames} @var{(local-nickname actual-package-name)}*
+
+The package has the specified local nicknames for the corresponding
+actual packages.
+@end itemize
+
+Example:
+
+@lisp
+(defpackage :bar (:intern "X"))
+(defpackage :foo (:intern "X"))
+(defpackage :quux (:use :cl) (:local-nicknames (:bar :foo) (:foo :bar)))
+(find-symbol "X" :foo) ; => FOO::X
+(find-symbol "X" :bar) ; => BAR::X
+(let ((*package* (find-package :quux)))
+ (find-symbol "X" :foo)) ; => BAR::X
+(let ((*package* (find-package :quux)))
+ (find-symbol "X" :bar)) ; => FOO::X
+@end lisp
+@end defmac
+
+@include fun-sb-ext-package-local-nicknames.texinfo
+@include fun-sb-ext-package-locally-nicknamed-by.texinfo
+@include fun-sb-ext-add-package-local-nickname.texinfo
+@include fun-sb-ext-remove-package-local-nickname.texinfo
+
+@node Package Variance
+@comment node-name, next, previous, up
+@section Package Variance
+
+Common Lisp standard specifies that ``If the new definition is at
+variance with the current state of that package, the consequences are
+undefined;'' SBCL by default signals a full warning and retains as
+much of the package state as possible.
+
+This can be adjusted using @code{sb-ext:*on-package-variance*}:
+
+@include var-sb-ext-star-on-package-variance-star.texinfo
+
@node Garbage Collection
@comment node-name, next, previous, up
@section Garbage Collection
+@cindex Garbage collection
SBCL provides additional garbage collection functionality not
-specified by ANSI. Weak pointers allow references to objects to be
-maintained without keeping them from being garbage collected, and
-``finalization'' hooks are available to cause code to be executed when
-an object has been garbage collected. Additionally users can specify
-their own cleanup actions to be executed with garbage collection. See
-also @code{make-hash-table} for information on weak hash tables.
+specified by ANSI.
+
+@include var-sb-ext-star-after-gc-hooks-star.texinfo
+@include fun-sb-ext-gc.texinfo
+
+@subsection Finalization
+@cindex Finalization
+
+Finalization allows code to be executed after an object has been
+garbage collected. This is useful for example for releasing foreign
+memory associated with a Lisp object.
@include fun-sb-ext-finalize.texinfo
@include fun-sb-ext-cancel-finalization.texinfo
+
+@subsection Weak Pointers
+@cindex Weak pointers
+
+Weak pointers allow references to objects to be maintained without
+keeping them from being garbage collected: useful for building caches
+among other things.
+
+Hash tables can also have weak keys and values: @pxref{Hash Table
+Extensions}.
+
@include fun-sb-ext-make-weak-pointer.texinfo
@include fun-sb-ext-weak-pointer-value.texinfo
-@include var-sb-ext-star-after-gc-hooks-star.texinfo
+
+@subsection Introspection and Tuning
+
+@include var-sb-ext-star-gc-run-time-star.texinfo
+@include fun-sb-ext-bytes-consed-between-gcs.texinfo
+@include fun-sb-ext-dynamic-space-size.texinfo
+@include fun-sb-ext-get-bytes-consed.texinfo
+@include fun-sb-ext-gc-logfile.texinfo
+@include fun-sb-ext-generation-average-age.texinfo
+@include fun-sb-ext-generation-bytes-allocated.texinfo
+@include fun-sb-ext-generation-bytes-consed-between-gcs.texinfo
+@include fun-sb-ext-generation-minimum-age-before-gc.texinfo
+@include fun-sb-ext-generation-number-of-gcs-before-promotion.texinfo
+@include fun-sb-ext-generation-number-of-gcs.texinfo
@node Metaobject Protocol
@comment node-name, next, previous, up
@section Metaobject Protocol
+@subsection AMOP Compatibility of Metaobject Protocol
+
SBCL supports a metaobject protocol which is intended to be compatible
with AMOP; present exceptions to this (as distinct from current bugs)
are:
@itemize
@item
-@findex compute-effective-method
-@findex sb-mop:compute-effective-method
+@findex @sbmop{compute-effective-method}
@code{compute-effective-method} only returns one value, not two.
There is no record of what the second return value was meant to
indicate, and apparently no clients for it.
@item
-@tindex generic-function
-@tindex standard-generic-function
-@tindex funcallable-standard-object
-@tindex sb-mop:funcallable-standard-object
-@tindex standard-object
-@tindex function
+@tindex @cl{generic-function}
+@tindex @cl{standard-generic-function}
+@tindex @sbmop{funcallable-standard-object}
+@tindex @cl{standard-object}
+@tindex @cl{function}
The direct superclasses of @code{sb-mop:funcallable-standard-object} are
@code{(function standard-object)}, not @code{(standard-object function)}.
ANSI specification.
@item
-@findex ensure-generic-function
-@findex generic-function-declarations
-@findex sb-mop:generic-function-declarations
+@findex @cl{ensure-generic-function}
+@findex @sbmop{generic-function-declarations}
the arguments @code{:declare} and @code{:declarations} to
@code{ensure-generic-function} are both accepted, with the leftmost
argument defining the declarations to be stored and returned by
@code{:declare}. Portable code should use @code{:declare}.
@item
-@findex validate-superclass
-@findex finalize-inheritance
-@findex sb-mop:validate-superclass
-@findex sb-mop:finalize-inheritance
-@tindex standard-class
-@tindex funcallable-standard-class
-@tindex sb-mop:funcallable-standard-class
-@tindex function
-@findex sb-mop:class-prototype
-@findex class-prototype
+@findex @sbmop{validate-superclass}
+@findex @sbmop{finalize-inheritance}
+@tindex @cl{standard-class}
+@tindex @sbmop{funcallable-standard-class}
+@tindex @cl{function}
+@findex @sbmop{class-prototype}
although SBCL obeys the requirement in AMOP that
@code{validate-superclass} should treat @code{standard-class} and
@code{funcallable-standard-class} as compatible metaclasses, we
@code{function} in its superclasses, and a class of metaclass
@code{standard-class} must not.
-@findex typep
-@findex class-of
-@findex subtypep
+@findex @cl{typep}
+@findex @cl{class-of}
+@findex @cl{subtypep}
After a class has been finalized, it is associated with a class
prototype which is accessible by a standard mop function
@code{sb-mop:class-prototype}. The user can then ask whether this
@end lisp
and leads to a class whose instances are funcallable and have one slot.
-@tindex funcallable-standard-object
-@tindex sb-mop:funcallable-standard-object
+@tindex @sbmop{funcallable-standard-object}
Note that this requirement also applies to the class
@code{sb-mop:funcallable-standard-object}, which has metaclass
@code{sb-mop:funcallable-standard-class} rather than
of software from colliding with each other.
@item
-@findex slot-value-using-class
-@findex sb-mop:slot-value-using-class
-@findex (setf slot-value-using-class)
-@findex (setf sb-mop:slot-value-using-class)
-@findex slot-boundp-using-class
-@findex sb-mop:slot-boundp-using-class
+@findex @sbmop{slot-value-using-class}
+@findex @setf{@sbmop{slot-value-using-class}}
+@findex @sbmop{slot-boundp-using-class}
specializations of the @code{new-value} argument to @code{(setf
sb-mop:slot-value-using-class)} are not allowed: all user-defined
methods must have a specializer of the class @code{t}.
argument of slot accessors.
@item
-@findex defclass
-@findex ensure-class
-@findex ensure-class-using-class
-@findex sb-mop:ensure-class
-@findex sb-mop:ensure-class-using-class
-@findex find-class
-@findex class-name
+@findex @cl{defclass}
+@findex @sbmop{ensure-class}
+@findex @sbmop{ensure-class-using-class}
+@findex @cl{find-class}
+@findex @cl{class-name}
the class named by the @code{name} argument to @code{ensure-class}, if
any, is only redefined if it is the proper name of that class;
otherwise, a new class is created.
@end itemize
+@subsection Metaobject Protocol Extensions
+
In addition, SBCL supports extensions to the Metaobject protocol from
AMOP; at present, they are:
@itemize
@item
-@findex defmethod
-@findex find-class
-@findex intern-eql-specializer
-@findex sb-mop:intern-eql-specializer
-@findex make-method-specializers-form
-@findex sb-pcl:make-method-specializers-form
-@findex make-method-lambda
-@findex sb-mop:make-method-lambda
+@findex @cl{defmethod}
+@findex @cl{find-class}
+@findex @sbmop{intern-eql-specializer}
+@findex @sbpcl{make-method-specializers-form}
+@findex @sbmop{make-method-lambda}
compile-time support for generating specializer metaobjects from
specializer names in @code{defmethod} forms is provided by the
@code{make-method-specializers-form} function, which returns a form
@var{x})} specializer name.
@item
-@findex find-method
-@findex parse-specializer-using-class
-@findex unparse-specializer-using-class
-@findex sb-pcl:parse-specializer-using-class
-@findex sb-pcl:unparse-specializer-using-class
+@findex @cl{find-method}
+@findex @sbpcl{parse-specializer-using-class}
+@findex @sbpcl{unparse-specializer-using-class}
run-time support for converting between specializer names and
specializer metaobjects, mostly for the purposes of
@code{find-method}, is provided by
between classes and proper names and between lists of the form
@code{(eql @var{x})} and interned eql specializer objects.
+@item
+@vindex @sbpcl{+slot-unbound+}
+@findex @sbmop{standard-instance-access}
+@findex @sbmop{funcallable-standard-instance-access}
+distinguishing unbound instance allocated slots from bound ones when
+using @code{standard-instance-access} and
+@code{funcallable-standard-instance-access} is possible by comparison
+to the constant @code{+slot-unbound+}.
+
@end itemize
@node Support For Unix
@section Support For Unix
@menu
-* Command-line arguments::
-* Querying the process environment::
-* Running external programs::
+* Command-line arguments::
+* Querying the process environment::
+* Running external programs::
@end menu
@node Command-line arguments
@subsection Command-line arguments
-@vindex sb-ext:*posix-argv*
-@vindex *posix-argv*
+@vindex @sbext{@earmuffs{posix-argv}}
The UNIX command line can be read from the variable
@code{sb-ext:*posix-argv*}.
@node Tools To Help Developers
@comment node-name, next, previous, up
@section Tools To Help Developers
-@findex trace
-@findex inspect
+@findex @cl{trace}
+@findex @cl{inspect}
SBCL provides a profiler and other extensions to the ANSI @code{trace}
facility. For more information, see @ref{Macro common-lisp:trace}.
@node Resolution of Name Conflicts
@section Resolution of Name Conflicts
-@tindex sb-ext:name-conflict
-@tindex name-conflict
-@findex sb-ext:name-conflict-symbols
-@findex name-conflict-symbols
+@tindex @sbext{name-conflict}
+@findex @sbext{name-conflict-symbols}
The ANSI standard (section 11.1.1.2.5) requires that name conflicts in
packages be resolvable in favour of any of the conflicting symbols. In
@node Hash Table Extensions
@comment node-name, next, previous, up
@section Hash Table Extensions
+@cindex Hash tables
Hash table extensions supported by SBCL are all controlled by keyword
arguments to @code{make-hash-table}.
@include fun-sb-ext-hash-table-weakness.texinfo
+@node Random Number Generation
+@comment node-name, next, previous, up
+@section Random Number Generation
+@cindex Random Number Generation
+
+The initial value of @code{*random-state*} is the same each time SBCL
+is started. This makes it possible for user code to obtain repeatable
+pseudo random numbers using only standard-provided functionality. See
+@code{seed-random-state} below for an SBCL extension that allows to
+seed the random number generator from given data for an additional
+possibility to achieve this. Non-repeatable random numbers can always
+be obtained using @code{(make-random-state t)}.
+
+The sequence of numbers produced by repeated calls to @code{random}
+starting with the same random state and using the same sequence of
+@code{limit} arguments is guaranteed to be reproducible only in the
+same version of SBCL on the same platform, using the same code under
+the same evaluator mode and compiler optimization qualities. Just two
+examples of differences that may occur otherwise: calls to
+@code{random} can be compiled differently depending on how much is
+known about the @code{limit} argument at compile time, yielding
+different results even if called with the same argument at run time,
+and the results can differ depending on the machine's word size, for
+example for limits that are fixnums under 64-bit word size but bignums
+under 32-bit word size.
+
+@include fun-sb-ext-seed-random-state.texinfo
+
+Some notes on random floats: The standard doesn't prescribe a specific
+method of generating random floats. The following paragraph describes
+SBCL's current implementation and should be taken purely informational,
+that is, user code should not depend on any of its specific properties.
+The method used has been chosen because it is common, conceptually
+simple and fast.
+
+To generate random floats, SBCL evaluates code that has an equivalent
+effect as
+@lisp
+(* limit
+ (float (/ (random (expt 2 23)) (expt 2 23)) 1.0f0))
+@end lisp
+(for single-floats) and correspondingly (with @code{52} and
+@code{1.0d0} instead of @code{23} and @code{1.0f0}) for double-floats.
+Note especially that this means that zero is a possible return value
+occurring with probability @code{(expt 2 -23)} respectively
+@code{(expt 2 -52)}. Also note that there exist twice as many
+equidistant floats between 0 and 1 as are generated. For example, the
+largest number that @code{(random 1.0f0)} ever returns is
+@code{(float (/ (1- (expt 2 23)) (expt 2 23)) 1.0f0)} while
+@code{(float (/ (1- (expt 2 24)) (expt 2 24)) 1.0f0)} is the
+largest single-float less than 1. This is a side effect of the fact
+that the implementation uses the fastest possible conversion from bits
+to floats.
+
+SBCL currently uses the Mersenne Twister as its random number
+generator, specifically the 32-bit version under both 32- and 64-bit
+word size. The seeding algorithm has been improved several times by
+the authors of the Mersenne Twister; SBCL uses the third version
+(from 2002) which is still the most recent as of June 2012. The
+implementation has been tested to provide output identical to the
+recommended C implementation.
+
+While the Mersenne Twister generates random numbers of much better
+statistical quality than other widely used generators, it uses only
+linear operations modulo 2 and thus fails some statistical
+tests@footnote{See chapter 7 "Testing widely used RNGs" in
+@cite{TestU01: A C Library for Empirical Testing of Random Number
+Generators} by Pierre L'Ecuyer and Richard Simard, ACM Transactions on
+Mathematical Software, Vol. 33, article 22, 2007.}.
+For example, the distribution of ranks of (sufficiently large) random
+binary matrices is much distorted compared to the theoretically
+expected one when the matrices are generated by the Mersenne Twister.
+Thus, applications that are sensitive to this aspect should use a
+different type of generator.
+
@node Miscellaneous Extensions
@comment node-name, next, previous, up
@section Miscellaneous Extensions
@include fun-sb-ext-array-storage-vector.texinfo
+@include fun-sb-ext-delete-directory.texinfo
+@include fun-sb-ext-get-time-of-day.texinfo
+@include macro-sb-ext-wait-for.texinfo
@node Stale Extensions
@comment node-name, next, previous, up
projects / sbcl.git / blobdiff