HACKING

   1 Here are some guidelines for members of the Guile developers team.
   2
   3 CVS conventions ======================================================
   4
   5 - We use CVS to manage the Guile sources.  The repository lives on
   6 egcs.cygnus.com, in /egcs/carton/cvsfiles; you will need an account on
   7 that machine to access the repository.  Also, for security reasons,
   8 egcs presently only supports CVS connections via the SSH protocol, so
   9 you must first install the SSH client.  Then, you should set your
  10 CVS_RSH environment variable to ssh, and use the following as your CVS
  11 root:
  12
  13         :ext:USER@egcs.cygnus.com:/egcs/carton/cvsfiles
  14
  15 Either set your CVSROOT environment variable to that, or give it as
  16 the value of the global -d option to CVS when you check out a working
  17 directory.
  18
  19 For more information on SSH, see http://www.cs.hut.fi/ssh.
  20
  21 The Guile sources live in several modules:
  22
  23   - guile-core --- the interpreter, QuickThreads, and ice-9
  24   - guile-doc --- documentation in progress.  When complete, this will
  25         be incorporated into guile-core.
  26   - guile-tcltk --- the Guile/Tk interface
  27   - guile-tk --- the new Guile/Tk interface, based on STk's modified Tk
  28   - guile-rgx-ctax --- the Guile/Rx interface, and the ctax implementation
  29   - guile-scsh --- the port of SCSH to guile, talk to Gary Houston
  30   - guile-comp --- the Hobbit compiler (talk to mdj)
  31   - guile-emacs --- Guile/Emacs interface (talk to mdj)
  32   - guile-oops --- The Guile Object-Oriented Programming System (talk to mdj)
  33   - guile-www --- A Guile module for making HTTP requests.
  34
  35 - We check Makefile.in and configure files into CVS, as well as the
  36 files they are built from (Makefile.am, configure.in); we do not check
  37 in Makefiles or header files generated by configuration scripts.  The
  38 general rule is that you should be able to check out a working
  39 directory of Guile from CVS, and then type "configure" and "make",
  40 without running any other tools.
  41
  42 - Make sure your changes compile and work, at least on your own
  43 machine, before checking them into the main branch of the Guile
  44 repository.  If you really need to check in untested changes, make a
  45 branch.
  46
  47 - Include each log entry in both the ChangeLog and in the CVS logs.
  48 If you're using Emacs, the pcl-cvs interface to CVS has features to
  49 make this easier; it checks the ChangeLog, and generates good default
  50 CVS log entries from that.
  51
  52
  53 Coding standards =====================================================
  54
  55 - As for any part of Project GNU, changes to Guile should follow the
  56 GNU coding standards.  The standards are available via anonymous FTP
  57 from prep.ai.mit.edu, as /pub/gnu/standards/standards.texi and
  58 make-stds.texi.
  59
  60 - The Guile tree should compile without warnings under the following
  61 GCC switches, which are the default in the current configure script:
  62     -O2 -Wall -Wpointer-arith -Wmissing-prototypes
  63 The only exceptions are the warnings about variables being clobbered
  64 by longjmp/vfork in eval.c.  (Tho' if you can figure out how to get
  65 rid of those, too, I'd be happy.)
  66
  67 Note that the warnings generated vary from one version of GCC to the
  68 next, and from one architecture to the next (apparently).  To provide
  69 a concrete common standard, Guile should compile without warnings from
  70 GCC 2.7.2.3 in a Red Hat 5.0 i386 Linux machine.  Furthermore, each
  71 developer should pursue any additional warnings noted by on their
  72 compiler.  This means that people using more stringent compilers will
  73 have more work to do, and assures that everyone won't switch to the
  74 most lenient compiler they can find.  :)
  75
  76 - When you make a user-visible change (i.e. one that should be
  77 documented, and appear in NEWS, put an asterisk in column zero of the
  78 start of the ChangeLog entry, like so:
  79
  80 Sat Aug  3 01:27:14 1996  Gary Houston  <ghouston@actrix.gen.nz>
  81
  82 *       * fports.c (scm_open_file): don't return #f, throw error.
  83
  84 When you've written a NEWS entry and updated the documentation, go
  85 ahead and remove the asterisk.  I will use the asterisks to find and
  86 document changes that haven't been dealt with before a release.
  87
  88 - There's no need to keep a change log for documentation files.  This
  89 is because documentation is not susceptible to bugs that are hard to
  90 fix.  Documentation does not consist of parts that must interact in a
  91 precisely engineered fashion; to correct an error, you need not know
  92 the history of the erroneous passage.  (This is copied from the GNU
  93 coding standards.)
  94
  95 - Make sure you have papers from people before integrating their
  96 changes or contributions.  This is very frustrating, but very
  97 important to do right.  From maintain.texi, "Information for
  98 Maintainers of GNU Software":
  99
 100     When incorporating changes from other people, make sure to follow the
 101     correct procedures.  Doing this ensures that the FSF has the legal
 102     right to distribute and defend GNU software.
 103
 104     For the sake of registering the copyright on later versions ofthe
 105     software you need to keep track of each person who makes significant
 106     changes.  A change of ten lines or so, or a few such changes, in a
 107     large program is not significant.
 108
 109     *Before* incorporating significant changes, make sure that the person
 110     has signed copyright papers, and that the Free Software Foundation has
 111     received them.
 112
 113 If you receive contributions you want to use from someone, let me know
 114 and I'll take care of the administrivia.  Put the contributions aside
 115 until we have the necessary papers.
 116
 117 - When you make substantial changes to a file, add the current year to
 118 the list of years in the copyright notice at the top of the file.
 119
 120
 121 Helpful hints ========================================================
 122
 123 - [From Mikael Djurfeldt] When working on the Guile internals, it is
 124 quite often practical to implement a scheme-level procedure which
 125 helps you examine the feature you're working on.
 126
 127 Examples of such procedures are: pt-size, debug-hand and
 128 current-pstate.
 129
 130 I've now put #ifdef GUILE_DEBUG around all such procedures, so that
 131 they are not compiled into the "normal" Guile library.  Please do the
 132 same when you add new procedures/C functions for debugging purpose.
 133
 134 You can define the GUILE_DEBUG flag by passing --enable-guile-debug to
 135 the configure script.
 136
 137 - You'll see uses of the macro SCM_P scattered throughout the code;
 138 those are vestiges of a time when Guile was meant to compile on
 139 pre-ANSI compilers.  Guile now requires ANSI C, so when you write new
 140 functions, feel free to use ANSI declarations, and please provide
 141 prototypes for everything.
 142
 143
 144 Jim Blandy