Guile Hacking Guide Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001 Free software Foundation, Inc. Permission is granted to anyone to make or distribute verbatim copies of this document as received, in any medium, provided that the copyright notice and permission notice are preserved, and that the distributor grants the recipient permission for further redistribution as permitted by this notice. Permission is granted to distribute modified versions of this document, or of portions of it, under the above conditions, provided also that they carry prominent notices stating who last changed them, and that any new or changed statements about the activities of the Free Software Foundation are approved by the Foundation. What to Hack ========================================================= You can hack whatever you want, thank GNU. However, to see what others have indicated as their interest (and avoid potential wasteful duplication of effort), see devel/tasks.text. Note that this file is available only from CVS checkout and not distributed w/ Guile releases. It's also a good idea to join the guile-devel@gnu.org mailing list. See http://www.gnu.org/software/guile/mail/mail.html for more info. Hacking It Yourself ================================================== As distributed, Guile needs only an ANSI C compiler and a Unix system to compile. However, Guile's makefiles, configuration scripts, and a few other files are automatically generated, not written by hand. If you want to make changes to the system (which we encourage!) you will find it helpful to have the tools we use to develop Guile. They are the following: Autoconf 2.50 --- a system for automatically generating `configure' scripts from templates which list the non-portable features a program would like to use. Available in "ftp://ftp.gnu.org/pub/gnu/autoconf" Automake 1.4-p2 --- a system for automatically generating Makefiles that conform to the (rather Byzantine) GNU coding standards. The nice thing is that it takes care of hairy targets like 'make dist' and 'make distclean', and automatically generates Makefile dependencies. Automake is available in "ftp://ftp.gnu.org/pub/gnu/automake" Before using automake, you may need to copy `threads.m4' and `guile.m4' from the top directory of the Guile core disty to `/usr/local/share/aclocal. libtool 1.4 --- a system for managing the zillion hairy options needed on various systems to produce shared libraries. Available in "ftp://ftp.gnu.org/pub/gnu/libtool" flex 2.5.4 (or newer) --- a scanner generator. earlier versions will most probably work too. You are lost in a little maze of automatically generated files, all different. Contributing Your Changes ============================================ - If you have put together a change that meets the coding standards described below, we encourage you to submit it to Guile. The best place to post it is guile-devel@gnu.org. Please don't send it directly to me; I often don't have time to look things over. If you have tested your change, then you don't need to be shy. - Please submit patches using either context or unified diffs (diff -c or diff -u). Don't include a patch for ChangeLog; such patches don't apply cleanly, since we've probably changed the top of ChangeLog too. Instead, provide the unaltered text at the top of your patch. Please don't include patches for generated files like configure, aclocal.m4, or any Makefile.in. Such patches are often large, and we're just going to regenerate those files anyway. CVS conventions ====================================================== - We use CVS to manage the Guile sources. The repository lives on subversions.gnu.org, in /cvs; you will need an account on that machine to access the repository. Also, for security reasons, subversions presently only supports CVS connections via the SSH protocol, so you must first install the SSH client. Then, you should set your CVS_RSH environment variable to ssh, and use the following as your CVS root: :ext:USER@subversions.gnu.org:/cvs Either set your CVSROOT environment variable to that, or give it as the value of the global -d option to CVS when you check out a working directory. For more information on SSH, see http://www.cs.hut.fi/ssh. The Guile sources live in several modules: - guile-core --- the interpreter, QuickThreads, and ice-9 - guile-tcltk --- the Guile/Tk interface - guile-tk --- the new Guile/Tk interface, based on STk's modified Tk - guile-rgx-ctax --- the Guile/Rx interface, and the ctax implementation - guile-scsh --- the port of SCSH to guile, talk to Gary Houston - guile-www --- A Guile module for making HTTP requests. There is a mailing list for CVS commit messages; see README for details. - We check Makefile.am and configure.in files into CVS, but the "autogen.sh" script must be run from the top-level to generate the actual "configure" script that then must be run to create the various Makefile-s to build guile. The general rule is that you should be able to check out a working directory of Guile from CVS, and then type "./autogen.sh", then "configure", and finally "make". No automatically generated files should be checked into the CVS repository. - The .cvsignore file is contained in the repository, to provide a reasonable list of auto-generated files that should not be checked in. This, however, prohibits one from having local additions to the .cvsignore file (yes, you can modify it and never check it in, but that doesn't seem to be a good solution to me). To get around this problem, you might want to patch your cvs program so that it uses a .cvsignore-local file (say) instead of the one from the repository. A patch for this can be found at the very end of this file. - (Automake 1.4 only) Be sure to run automake at the top of the tree with no arguments. Do not use `automake Makefile' to regenerate specific Makefile.in files, and do not trust the Makefile rules to rebuild them when they are out of date. Automake 1.4 will add extraneous rules to the top-level Makefile if you specify specific Makefiles to rebuild on the command line. Running the command `autoreconf --force' should take care of everything correctly. - Make sure your changes compile and work, at least on your own machine, before checking them into the main branch of the Guile repository. If you really need to check in untested changes, make a branch. - Include each log entry in both the ChangeLog and in the CVS logs. If you're using Emacs, the pcl-cvs interface to CVS has features to make this easier; it checks the ChangeLog, and generates good default CVS log entries from that. Coding standards ===================================================== - Before contributing larger amounts of code to Guile, please read the documents in `guile-core/devel/policy' in the CVS source tree. - As for any part of Project GNU, changes to Guile should follow the GNU coding standards. The standards are available via anonymous FTP from prep.ai.mit.edu, as /pub/gnu/standards/standards.texi and make-stds.texi. - The Guile tree should compile without warnings under the following GCC switches, which are the default in the current configure script: -O2 -Wall -Wpointer-arith -Wmissing-prototypes Note that the warnings generated vary from one version of GCC to the next, and from one architecture to the next (apparently). To provide a concrete common standard, Guile should compile without warnings from GCC 2.7.2.3 in a Red Hat 5.2 i386 Linux machine. Furthermore, each developer should pursue any additional warnings noted by on their compiler. This means that people using more stringent compilers will have more work to do, and assures that everyone won't switch to the most lenient compiler they can find. :) Note also that EGCS (as of November 3 1998) doesn't handle the `noreturn' attribute properly, so it doesn't understand that functions like scm_error won't return. This may lead to some silly warnings about uninitialized variables. You should look into these warnings to make sure they are indeed spurious, but you needn't correct warnings caused by this EGCS bug. - If you add code which uses functions or other features that are not entirely portable, please make sure the rest of Guile will still function properly on systems where they are missing. This usually entails adding a test to configure.in, and then adding #ifdefs to your code to disable it if the system's features are missing. - The normal way of removing a function, macro or variable is to mark it as "deprecated", keep it for a while, and remove it in a later release. If a function or macro is marked as "deprecated" it indicates that people shouldn't use it in new programs, and should try to remove it in old. Make sure that an alternative exists unless it is our purpose to remove functionality. Don't deprecate definitions if it is unclear when they will be removed. (This is to ensure that a valid way of implementing some functionality always exists.) When deprecating a definition, always follow this procedure: 1. Mark the definition using #if (SCM_DEBUG_DEPRECATED == 0) ... #endif or, for Scheme code, wrap it using (begin-deprecated ...) 2. Make the deprecated code issue a warning when it is used, by using scm_c_issue_deprecation_warning (in C) or issue-deprecation-warning (in Scheme). 3. Write a comment at the definition explaining how a programmer can manage without the deprecated definition. 4. Add an entry that the definition has been deprecated in NEWS and explain what do do instead. 5. At the top of RELEASE, there is a list of releases with reminders about what to do at each release. Add a reminder about the removal of the deprecated defintion at the appropriate release. - When you make a user-visible change (i.e. one that should be documented, and appear in NEWS, put an asterisk in column zero of the start of the ChangeLog entry, like so: Sat Aug 3 01:27:14 1996 Gary Houston * * fports.c (scm_open_file): don't return #f, throw error. When you've written a NEWS entry and updated the documentation, go ahead and remove the asterisk. I will use the asterisks to find and document changes that haven't been dealt with before a release. - Please write log entries for functions written in C under the functions' C names, and write log entries for functions written in Scheme under the functions' Scheme names. Please don't do this: * procs.c, procs.h (procedure-documentation): Moved from eval.c. Entries like this make it harder to search the ChangeLogs, because you can never tell which name the entry will refer to. Instead, write this: * procs.c, procs.h (scm_procedure_documentation): Moved from eval.c. Changes like adding this line are special: SCM_PROC (s_map_in_order, "map-in-order", 2, 0, 1, scm_map); Since the change here is about the name itself --- we're adding a new alias for scm_map that guarantees the order in which we process list elements, but we're not changing scm_map at all --- it's appropriate to use the Scheme name in the log entry. - There's no need to keep a change log for documentation files. This is because documentation is not susceptible to bugs that are hard to fix. Documentation does not consist of parts that must interact in a precisely engineered fashion; to correct an error, you need not know the history of the erroneous passage. (This is copied from the GNU coding standards.) - Make sure you have papers from people before integrating their changes or contributions. This is very frustrating, but very important to do right. From maintain.texi, "Information for Maintainers of GNU Software": When incorporating changes from other people, make sure to follow the correct procedures. Doing this ensures that the FSF has the legal right to distribute and defend GNU software. For the sake of registering the copyright on later versions ofthe software you need to keep track of each person who makes significant changes. A change of ten lines or so, or a few such changes, in a large program is not significant. *Before* incorporating significant changes, make sure that the person has signed copyright papers, and that the Free Software Foundation has received them. If you receive contributions you want to use from someone, let me know and I'll take care of the administrivia. Put the contributions aside until we have the necessary papers. Once you accept a contribution, be sure to keep the files AUTHORS and THANKS uptodate. - When you make substantial changes to a file, add the current year to the list of years in the copyright notice at the top of the file. - When you get bug reports or patches from people, be sure to list them in THANKS. - Naming conventions. We use certain naming conventions to structure the considerable number of global identifiers. All identifiers should be either all lower case or all upper case. Syllables are separated by underscaores `_'. All non-static identifiers should start with scm_ or SCM_. Then might follow zero or more one letter syllables giving the category of the identifier. The currently used category identifiers are t - type name c,C - something with a interface suited for C use. This is used to name functions that behave like Scheme primitives but have a more C friendly calling convention. i,I - internal to libguile. It is global, but not considered part of the libguile API. f - a SCM variable pointing to a Scheme function object. F - a bit mask for a flag. m - a macro transformer procedure n,N - a count of something s - a constant C string Helpful hints ======================================================== - [From Mikael Djurfeldt] When working on the Guile internals, it is quite often practical to implement a scheme-level procedure which helps you examine the feature you're working on. Examples of such procedures are: pt-size, debug-hand and current-pstate. I've now put #ifdef GUILE_DEBUG around all such procedures, so that they are not compiled into the "normal" Guile library. Please do the same when you add new procedures/C functions for debugging purpose. You can define the GUILE_DEBUG flag by passing --enable-guile-debug to the configure script. - You'll see uses of the macro SCM_P scattered throughout the code; those are vestiges of a time when Guile was meant to compile on pre-ANSI compilers. Guile now requires ANSI C, so when you write new functions, feel free to use ANSI declarations, and please provide prototypes for everything. You don't need to use SCM_P in new code. Jim Blandy, and others Patches =========================================================== This one makes cvs-1.10 consider the file $CVSDOTIGNORE instead of .cvsignore when that environment variable is set. === patch start === diff -r -u cvs-1.10/src/cvs.h cvs-1.10.ignore-hack/src/cvs.h --- cvs-1.10/src/cvs.h Mon Jul 27 04:54:11 1998 +++ cvs-1.10.ignore-hack/src/cvs.h Sun Jan 23 12:58:09 2000 @@ -516,7 +516,7 @@ extern int ign_name PROTO ((char *name)); void ign_add PROTO((char *ign, int hold)); -void ign_add_file PROTO((char *file, int hold)); +int ign_add_file PROTO((char *file, int hold)); void ign_setup PROTO((void)); void ign_dir_add PROTO((char *name)); int ignore_directory PROTO((char *name)); diff -r -u cvs-1.10/src/ignore.c cvs-1.10.ignore-hack/src/ignore.c --- cvs-1.10/src/ignore.c Mon Sep 8 01:04:15 1997 +++ cvs-1.10.ignore-hack/src/ignore.c Sun Jan 23 12:57:50 2000 @@ -99,9 +99,9 @@ /* * Open a file and read lines, feeding each line to a line parser. Arrange * for keeping a temporary list of wildcards at the end, if the "hold" - * argument is set. + * argument is set. Return true when the file exists and has been handled. */ -void +int ign_add_file (file, hold) char *file; int hold; @@ -149,8 +149,8 @@ if (fp == NULL) { if (! existence_error (errno)) - error (0, errno, "cannot open %s", file); - return; + error (0, errno, "cannot open %s", file); + return 0; } while (getline (&line, &line_allocated, fp) >= 0) ign_add (line, hold); @@ -159,6 +159,7 @@ if (fclose (fp) < 0) error (0, errno, "cannot close %s", file); free (line); + return 1; } /* Parse a line of space-separated wildcards and add them to the list. */ @@ -375,6 +376,7 @@ struct stat sb; char *file; char *xdir; + char *cvsdotignore; /* Set SUBDIRS if we have subdirectory information in ENTRIES. */ if (entries == NULL) @@ -397,7 +399,10 @@ if (dirp == NULL) return; - ign_add_file (CVSDOTIGNORE, 1); + cvsdotignore = getenv("CVSDOTIGNORE"); + if (cvsdotignore == NULL || !ign_add_file (cvsdotignore, 1)) + ign_add_file (CVSDOTIGNORE, 1); + wrap_add_file (CVSDOTWRAPPER, 1); while ((dp = readdir (dirp)) != NULL) === patch end === This one is for pcl-cvs-2.9.2, so that `i' adds to the local .cvsignore file. === patch start === --- pcl-cvs.el~ Mon Nov 1 12:33:46 1999 +++ pcl-cvs.el Tue Jan 25 21:46:27 2000 @@ -1177,7 +1177,10 @@ "Append the file in FILEINFO to the .cvsignore file. Can only be used in the *cvs* buffer." (save-window-excursion - (set-buffer (find-file-noselect (expand-file-name ".cvsignore" dir))) + (set-buffer (find-file-noselect + (expand-file-name (or (getenv "CVSDOTIGNORE") + ".cvsignore") + dir))) (goto-char (point-max)) (unless (zerop (current-column)) (insert "\n")) (insert str "\n") === patch end ===