[Module-build-general] [PATCH] Make Compat.pm play well with old CPAN(PLUS)?.pm.

[Autrijus T. <aut...@au...>]

As attached.  Two things are fixed:

- PREREQ_PM info is now written to Makefile.
- Friendly bootstrapping code that makes Module::Build to
  be installed first.

I hadn't tested extensively whether old CPAN.pm will resume
from 'perl Makefile.PL' step or merely 'make'.  If it's
the latter case then we also need a fake 'all :' target
that runs 'Build.PL' again in the POD.

Thanks,
/Autrijus/

--- lib/Module/Build/Compat.pm	Wed Jun  5 11:25:43 2002
+++ /home/autrijus/Compat.pm	Thu Aug 15 18:52:39 2002
@@ -36,12 +36,31 @@
 EOF
 }
 
-sub write_makefile {
-  # Note - this doesn't yet emulate the PREREQ_PM stuff.
+sub fake_prereqs {
+  my ($pack, %in) = @_;
+  $in{metadata} ||= 'META.yaml';
+
+  my @prereq;
+  foreach my $section (qw/build_requires requires/) {
+    # parse YAML's prerequisite info
+    open META, $in{metadata} or die "Cannot read $in{metadata}: $!";
+    while (<META>) {
+      next if (1 .. /^$section:$/);
+      last unless /^  (.*): (.*)$/;
+      push @prereq, "$1=>q[$2]" unless $1 eq 'perl';
+    }
+    close META;
+  }
 
+  return unless @prereq;
+  return "#     PREREQ_PM => { " . join(", ", @prereq) . " }\n\n";
+}
+
+sub write_makefile {
   my ($pack, %in) = @_;
   $in{makefile} ||= 'Makefile';
   open  MAKE, "> $in{makefile}" or die "Cannot write $in{makefile}: $!";
+  print MAKE $pack->fake_prereqs;
   print MAKE $pack->fake_makefile;
   close MAKE;
 }
@@ -58,7 +77,16 @@
 
  Here's a Makefile.PL that passes all functionality through to Module::Build
  
-  use Module::Build::Compat;
+  unless (eval { require Module::Build::Compat; 1 }) {
+      # Workaround with old CPAN.pm and CPANPLUS.pm
+      require ExtUtils::MakeMaker;
+      ExtUtils::MakeMaker::WriteMakefile(
+	  'PREREQ_PM' => { 'Module::Build::Compat' => 0 }
+      );
+      warn "Warning: prerequisite Module::Build::Compat is not found.\n";
+      exit(0);
+  }
+
   Module::Build::Compat->run_build_pl(args => \@ARGV);
   Module::Build::Compat->write_makefile();