package ExtUtils::MakeMaker::FAQ;

our $VERSION = '0.01';

1;
__END__

=head1 NAME

ExtUtils::MakeMaker::FAQ - Frequently Asked Questions About MakeMaker

=head1 SYNOPSIS

=head1 DESCRIPTION

Document tips and tricks for C<ExtUtils::MakeMaker>.

=over 4

=item How do I make two or more XS files coexist in the same directory?

Sometimes you need to have two and more XS files in the same package.
One way to go is to put them into separate directories, but sometimes
this is not the most suitable solution. The following technique allows
you to put two (and more) XS files in the same directory.

Let's assume that we have a package C<Cool::Foo>, which includes
C<Cool::Foo> and C<Cool::Bar> modules each having a separate XS
file. First we use the following I<Makefile.PL>:

  use ExtUtils::MakeMaker;
  
  WriteMakefile(
      NAME		=> 'Cool::Foo',
      VERSION_FROM	=> 'Foo.pm',
      OBJECT              => q/$(O_FILES)/,
      # ... other attrs ...
  );

Notice the C<OBJECT> attribute. MakeMaker generates the following
variables in I<Makefile>:

  # Handy lists of source code files:
  XS_FILES= Bar.xs \
  	Foo.xs
  C_FILES = Bar.c \
  	Foo.c
  O_FILES = Bar.o \
  	Foo.o

Therefore we can use the C<O_FILES> variable to tell MakeMaker to use
these objects into the shared library.

That's pretty much it. Now write I<Foo.pm> and I<Foo.xs>, I<Bar.pm>
and I<Bar.xs>, where I<Foo.pm> bootstraps the shared library and
I<Bar.pm> simply loading I<Foo.pm>.

The only issue left is to how to bootstrap I<Bar.xs>. This is done
from I<Foo.xs>:

  MODULE = Cool::Foo PACKAGE = Cool::Foo
  
  BOOT:
  # boot the second XS file
  boot_Cool__Bar(aTHX_ cv);

If you have more than two files, this is the place where you should
boot extra XS files from.

The following four files sum up all the details discussed so far.

  Foo.pm:
  -------
  package Cool::Foo;
  
  require DynaLoader;
  
  our @ISA = qw(DynaLoader);
  our $VERSION = '0.01';
  bootstrap Cool::Foo $VERSION;
  
  1;
  
  Bar.pm:
  -------
  package Cool::Bar;
  
  use Cool::Foo; # bootstraps Bar.xs
  
  1;

  Foo.xs:
  -------
  #include "EXTERN.h"
  #include "perl.h"
  #include "XSUB.h"
  
  MODULE = Cool::Foo  PACKAGE = Cool::Foo
  
  BOOT:
  # boot the second XS file
  boot_Cool__Bar(aTHX_ cv);
  
  MODULE = Cool::Foo  PACKAGE = Cool::Foo  PREFIX = cool_foo_
  
  void
  cool_foo_perl_rules()
  
      CODE:
      fprintf(stderr, "Cool::Foo says: Perl Rules\n");

  Bar.xs:
  -------
  #include "EXTERN.h"
  #include "perl.h"
  #include "XSUB.h"
  
  MODULE = Cool::Bar  PACKAGE = Cool::Bar PREFIX = cool_bar_
  
  void
  cool_bar_perl_rules()
  
      CODE:
      fprintf(stderr, "Cool::Bar says: Perl Rules\n");

And of course a very basic test:

  test.pl:
  --------
  use Test;
  BEGIN { plan tests => 1 };
  use Cool::Foo;
  use Cool::Bar;
  Cool::Foo::perl_rules();
  Cool::Bar::perl_rules();
  ok 1;

This tip has been brought to you by Nick Ing-Simmons and Stas Bekman.

=back

=head1 PATCHING

If you have a question you'd like to see added to the FAQ (whether or
not you have the answer) please send it to makemaker@perl.org.

=head1 AUTHOR

The denizens of makemaker@perl.org.

=head1 SEE ALSO

L<ExtUtils::MakeMaker>

=cut
