[Module-build-general] A better passthrough Makefile.PL

[Dave R. <au...@ur...>]

I wanted to create a Makefile.PL that would pass all functionality through
to Module::Build, _and_ that would make sure that Module::Build got
installed if necessary.  I also wanted to make sure that the user did not
have to run "perl Makefile.PL" twice, once for installing Module::Build,
and once to install the desired module.  Having to do this basically makes
the install fail with CPAN or CPANPLUS.

Here's what I came up with:


  use Cwd;
  use File::Spec;

  unless (eval { require Module::Build::Compat; 1 }) {
      require ExtUtils::MakeMaker;

      print "This module required Module::Build to install itself.\n";

      my $yn = ExtUtils::MakeMaker::prompt( '  Install Module::Build', 'y' );

      if ($yn =~ /^y(es)?/i) {
	  # save this cause CPAN will chdir all over the place.
	  my $cwd = cwd();
	  my $makefile = File::Spec->rel2abs($0);

	  require CPAN;
	  CPAN->install('Module::Build');

	  chdir $cwd
	      or die "Cannot chdir to $cwd: $!";

	  exec( $^X, $makefile, @ARGV )
      } else {
	  warn "Cannot install Thesaurus without Module::Build.  Exiting ...\n";
	  exit 0;
      }
  }

  require Module::Build::Compat;
  Module::Build::Compat->run_build_pl( args => \@args );
  Module::Build::Compat->write_makefile;