Accumulation of half-understood design decisions eventually chokes a program as a water weed chokes a canal. By refactoring you can ensure that your full understanding of how the program should be designed is always reflected in the program. As a water weed quickly spreads its tendrils, partially understood design decisions quickly spread their effects throughout your program. No one or two or even ten individual actions will be enough to eradicate the problem. -- Martin Fowler, _Refactoring: Improving the Design of Existing Code_, p. 360 =============================================================================== some things that I'd like to do in 0.6.x, in no particular order: ------------------------------------------------------------------------------- PROBLEM: The batch-related command line options for SBCL don't work properly. A small part of making them work properly is making sure that verbose GC messages end up piped to error output. Make sure that when the system dies due to an unhandled error in batch mode, the error is printed successfully, whether FINISH-OUTPUT or an extra newline or whatever is required. Make sure that make.sh dies gracefully when one of the SBCLs it's running dies with an error. MUSING: Actually, the ANSI *DEBUGGER-HOOK* variable might be a better place to put the die-on-unhandled-error functionality. FIX: ?? ------------------------------------------------------------------------------- PROBLEM: As long as I'm working on the batch-related command-line options, it would be reasonable to add one more option to "do what I'd want", testing standard input for non-TTY-ness and running in no-programmer mode if so. FIX: ?? Do it. ------------------------------------------------------------------------------- PROBLEM: In order to make a well-behaved backtrace when a batch program terminates abnormally, it should be limited in length. FIX: ?? Add a *DEBUG-BACKTRACE-COUNT* variable, initially set to 64, to provide a default for the COUNT argument to BACKTRACE. ------------------------------------------------------------------------------- PROBLEM: I used CMU CL for years, and dozens of times I cursed the inadequate breakpoint-based TRACE facility which doesn't work on some functions, and I never realized that there's a wrapper-based facility too until I was wading through the source code for SBCL. Yes, I know I should have RTFM, but there is a lot of M.. (By the way, it would also be nice to have tracing behave better with generic functions. TRACEing a generic function probably shouldn't prevent DEFMETHOD from being used to redefine its methods, and should perhaps trace each of its methods as well as the generic function itself.) FIX: ?? possibility 1: Add error-handling code in ntrace.lisp to catch failure to set breakpoints and retry using wrapper-based tracing. ?? possibility 2: Add error-handling code in ntrace.lisp to catch failure to catch failure to set breakpoints and output a message suggesting retrying with wrapper-based breakpoints ?? possibility 3: Fix the breakpoint-based TRACE facility so that it always works. ------------------------------------------------------------------------------- PROBLEM: When cross-compiling host-byte-comp.lisp, I get bogus warnings caught STYLE-WARNING: undefined function: %%DEFCONSTANT caught STYLE-WARNING: This function is undefined: %%DEFCONSTANT MUSING: The best way to clean this up would be as a side-effect of a larger cleanup, making all the %%DEFFOO stuff use EVAL-WHEN instead of IR1 magic. There's probably some way to do it with a quick local hack too. FIX: ?? ------------------------------------------------------------------------------- PROBLEM: My system of parallel build directories seems to add complexity without adding value. FIX: ?? Replace it with a system where fasl output files live in the same directories as the sources and have names a la "foo.fasl-from-host and "foo.fasl-from-xc". ------------------------------------------------------------------------------- PROBLEM: It might be good to use the syntax (DEBUGGER-SPECIAL *PRINT-LEVEL*) etc. to control the in-the-debug-context special variables. Then we wouldn't have to pick and choose which variables we shadow in the debugger. The shadowing values could also be made persistent between debugger invocations, so that entering the debugger, doing (SETF *PRINT-LEVEL* 2), and exiting the debugger would leave (DEBUGGER-SPECIAL *PRINT-LEVEL*) set to 2, and upon reentry to the debugger, *PRINT-LEVEL* would be set back to 2. FIX: ?? ------------------------------------------------------------------------------- PROBLEM: The :SB-TEST target feature should do something. FIX: ?? ------------------------------------------------------------------------------- PROBLEM: I still haven't cleaned up the cut-and-paste programming in * DEF-BOOLEAN-ATTRIBUTE, DELETEF-IN, and PUSH-IN * SB!SYS:DEF!MACRO ASSEMBLE and SB!XC:DEFMACRO ASSEMBLE FIX: ?? ------------------------------------------------------------------------------- PROBLEM: We be able to get rid of the IR1 interpreter, which would not only get rid of all the code in *eval*.lisp, but also allow us to reduce the number of special cases elsewhere in the system. (Try grepping for 'interpret' sometime.:-) Making this usable might require cleaning up %DEFSTRUCT, %DEFUN, etc. to use EVAL-WHEN instead of IR1 transform magic, which would be a good thing in itself, but might be a fair amount of work.) FIX: ?? Delete, delete, delete. ------------------------------------------------------------------------------- PROBLEM: The hashing code is new and should be tested. FIX: ?? Enable the existing test code. =============================================================================== other known issues with no particular target date: user manual including, at a minimum, updated versions of the CMU CL user manual information on the compiler and the alien interface bugs listed on the man page more regression tests various bugs fixed in CMUCL since this code was forked off of it ca. 19980801, since most of these haven't been fixed yet in SBCL byte compilation of appropriate parts of the system, so that the system core isn't so big uninterning needed-only-at-init-time stuff after init is complete, so that the system core isn't so big Search for unused external symbols (ones which are not bound, fbound, types, or whatever, and also have no other uses as e.g. flags) and delete them. This should make the system core a little smaller, but is mostly useful just to make the source code smaller and simpler. The eventual plan is for SBCL to bootstrap itself in two phases. In the first phase, the cross-compilation host is any old ANSI Common Lisp (not necessarily SBCL) and the cross-compiler won't handle some optimizations because the code it uses to implement them is not portable. In the second phase, the cross-compilation host will be required to be a compatible version of SBCL, and the cross-compiler will take advantage of that to implement all optimizations. The current version of SBCL only knows how to do the first of those two phases, with a fully-portable cross-compiler, so some optimizations are not done. Probably the most important consequence of this is that because the fully-portable cross-compiler isn't very smart about dealing with immediate values which are of specialized array type (e.g. (SIMPLE-ARRAY (UNSIGNED-BYTE 4) 1)) the system sometimes has to use unnecessarily-general array types internally. adding new FOPs to provide something like CMU CL's FOP-SYMBOL-SAVE and FOP-SMALL-SYMBOL-SAVE functionality, so that fasl files will be more compact. (FOP-SYMBOL-SAVE used *PACKAGE*, which was concise but allowed obscure bugs. Something like FOP-LAST-PACKAGE-SYMBOL-SAVE could have much of the same conciseness advantage without the bugs.) hundreds of FIXME notes in the sources from WHN various other unfinished business from CMU CL and before, marked with "XX" or "XXX" or "###" or "***" or "???" or "pfw" or "@@@@" or "zzzzz" or probably also other codes that I haven't noticed or have forgotten. (Things marked as KLUDGE are in general things which are ugly or confusing, but that, for whatever reason, may stay that way indefinitely.)