hook patch for Automake extension

[Fabrice Salvaire]

Hello,

I wrote 2 patches for Automake:

 - 1) one for SWIG (Simplified Wrapper and Interface Generator, 
http://www.swig.org/)
 
   from a fork of LTLIBRARIES: sub handle_swig
 
 - 2) another for Cint, a C++ interpretor used mainly in particle physics 
research.
 
   I added 2 variables
 
     _SOURCES_CINT_DICT =
     _CINTFLAGS =
 
   The trick consist to complete automaticly _SOURCE with the sources generated
   by Cint from the definition of _SOURCES_CINT_DICT. It's look like
   Lex/Yacc, but with an horrible design ...
 
     for example, the implementation in LTLIBRARIES is:
 
     ...
 
     &handle_source_cint ($xname, $where); # complete _SOURCES before:
 
     my $linker = &handle_source_transform ($xname, $one_file, $obj, $where,
                                             NONLIBTOOL => 1, LIBTOOL => 0);
 
     ...


  As it was told in the mailing list, Automake can't support all minor
development. Except if Automake is modularised.

  So, I wrote a short patch (look at the end of my mail) to add a
simple hook system to Automake. The hook are located in the
strategical place in the Automake source code. For example:

    Hook::Manager::instance->execute_hook ('handle_source', $xname, $where);

The module are specified like this

  automake -m Foo.pm

or with (to be implemented)

  AM_INIT_AUTOMAKE([Foo.pm])

The module are searched in the PERL5LIB env.

Then, when the module is initialised, it add this callback like this:

  sub BEGIN
  {
    Hook::Manager::instance->register_hook ('handle_source', 
\&handle_source_cint);
  }

I think this patch resolve simply and quickly the problem to create
and maintain extension to Automake. It's probably possible to do a
better design. But I'm not sure of this interest at short-term. The
aim isn't to redesign the Autotools. But to add the possibility to
maintain extension, now.

cheers,

Fabrice Salvaire


================= The hook patch: =================

--- automake-1.9.5-ref/automake.in      2005-02-12 11:06:56.000000000 +0100
+++ automake-1.9.5-dev/automake.in      2005-05-06 06:44:57.000000000 +0200
@@ -141,6 +141,7 @@
 use Automake::Rule;
 use Automake::RuleDef;
 use Automake::Wrap 'makefile_wrap';
+use Automake::Hook;
 use File::Basename;
 use Carp;
 
@@ -2264,6 +2265,8 @@
       $where->push_context ("while processing program `$one_file'");
       $where->set (INTERNAL->get);
 
+      Hook::Manager::instance->execute_hook ('handle_source', $xname, $where);
+
       my $linker = &handle_source_transform ($xname, $one_file, $obj, $where,
                                             NONLIBTOOL => 1, LIBTOOL => 0);
 
@@ -2581,6 +2595,7 @@
       reject_var ("${xlib}_LDADD",
                  "use `${xlib}_LIBADD', not `${xlib}_LDADD'");
 
+      Hook::Manager::instance->execute_hook ('handle_source', $xlib, $where);
 
       my $linker = &handle_source_transform ($xlib, $onelib, $obj, $where,
                                             NONLIBTOOL => 0, LIBTOOL => 1);
@@ -6374,6 +6389,27 @@
 
 
 # $CONTENTS
+# &find_am_file ($BASENAME)
+# ------------------------------------------------
+# 
+# 
+sub find_am_file ($)
+{
+  my ($basename) = @_;
+  
+  foreach my $dir (@libdir)
+    {
+      my $file = "$dir/am/$basename.am";
+      
+      return $file if (-e $file);
+    }
+
+  # error
+  die "file am/$basename.am not found in @libdir\n";
+}
+
+
+# $CONTENTS
 # &file_contents ($BASENAME, $WHERE, [%TRANSFORM])
 # ------------------------------------------------
 # Return contents of a file from $libdir/am, automatically skipping
@@ -6381,8 +6417,9 @@
 sub file_contents ($$%)
 {
     my ($basename, $where, %transform) = @_;
+
     my ($comments, $variables, $rules) =
-      file_contents_internal (1, "$libdir/am/$basename.am", $where,
+      file_contents_internal (1, find_am_file ($basename), $where,
                              %transform);
     return "$comments$variables$rules";
 }
@@ -7151,6 +7188,7 @@
   handle_gettext;
   handle_libraries;
   handle_ltlibraries;
+  Hook::Manager::instance->execute_hook ('handle_libraries');
   handle_programs;
   handle_scripts;
 
@@ -7396,6 +7434,7 @@
      # compatibility.  Use -Werror and -Wno-error today.
      'Werror'           => sub { parse_warnings 'W', 'error'; },
      'Wno-error'        => sub { parse_warnings 'W', 'no-error'; },
+     'm|module:s'       => sub { Hook::Manager::instance->push_module ($_[1]) 
},
      );
   use Getopt::Long;
   Getopt::Long::config ("bundling", "pass_through");
@@ -7471,6 +7510,9 @@
 
 $configure_ac = require_configure_ac;
 
+# Init the hook manager
+Hook::Manager::instance->init ();
+
 # Do configure.ac scan only once.
 scan_autoconf_files;
 
--- automake-1.9.5-ref/lib/Automake/Hook.pm     1970-01-01 01:00:00.000000000 
+0100
+++ automake-1.9.5-dev/lib/Automake/Hook.pm     2005-05-06 06:39:30.000000000 
+0200
@@ -0,0 +1,86 @@
+package Hook::Manager;
+
+use 5.005;
+use warnings;
+use strict;
+
+use File::Basename;
+ 
+our $instance;
+
+sub instance
+{
+  $instance = new Hook::Manager unless ($instance);
+
+  return $instance;
+}
+
+sub new
+{
+  my $invocant = shift;
+  my $class = ref ($invocant) || $invocant;
+
+  my $obj = bless ({}, $class);
+
+  $obj->{modules} = [];
+
+  $obj->{hooks} = {};
+
+  return $obj;
+}
+
+sub push_module
+{
+  my ($obj, @module) = @_;
+
+  my $module_list = $obj->{modules};
+
+  push @$module_list, @module;
+}
+
+sub init
+{
+  my $obj = shift;
+
+  my $module_list = $obj->{modules};
+
+  foreach my $module (@$module_list)
+  {
+    require $module; # error ?
+
+    my ($name, $path, $suffix) = fileparse ($module, '.am');
+
+    push @Automake::libdir, $path;
+
+    $module::libdir = $path;
+  }
+}
+
+sub register_hook #($$&)
+{
+  my ($obj, $name, $callback) = @_;
+
+  push @{$obj->{hooks}{$name}}, $callback;
+
+  print STDERR "Register Hook $name\n";
+}
+
+sub execute_hook
+{
+  my $obj  = shift;
+  my $name = shift;
+
+  if (my $hook_list = $obj->{hooks}{$name})
+  {
+    foreach my $callback (@$hook_list)
+    {
+      &$callback (@_);
+    }
+  }
+}
+
+1;