ExtUtils::Depends(3)

NAME
ExtUtils::Depends - Easily build XS extensions that depend on XS extensions

SYNOPSIS
        use ExtUtils::Depends;
        $package = new ExtUtils::Depends ('pkg::name', 'base::package')
        # set the flags and libraries to compile and link the module
        $package->set_inc("-I/opt/blahblah");
        $package->set_libs("-lmylib");
        # add a .c and an .xs file to compile
        $package->add_c('code.c');
        $package->add_xs('module-code.xs');
        # add the typemaps to use
        $package->add_typemaps("typemap");
        # install some extra data files and headers
        $package->install (qw/foo.h data.txt/);
        # save the info
        $package->save_config('Files.pm');

        WriteMakefile(
                'NAME' => 'Mymodule',
                $package->get_makefile_vars()
        );

DESCRIPTION
This module tries to make it easy to build Perl extensions that use functions and typemaps provided by other perl extensions. This means that a perl extension is treated like a shared library that provides also a C and an XS interface besides the perl one.

This works as long as the base (or "producing") extension is loaded with the "RTLD_GLOBAL" flag (usually done with a

        sub dl_load_flags {0x01}

in the main .pm file) if you need to use functions defined in the module. That "producing" extension will also need to tell ExtUtils::MakeMaker the specific functions to export, with arguments to "WriteMakefile" like:

  FUNCLIST => [qw(function_name)],
  DL_FUNCS => { 'Extension::Name' => [] },

The basic scheme of operation is to collect information about a module in the instance, and then store that data in the Perl library where it may be retrieved later. The object can also reformat this information into the data structures required by ExtUtils::MakeMaker's WriteMakefile function.

For information on how to make your module fit into this scheme, see "hashref = ExtUtils::Depends::load (name)".

When creating a new Depends object, you give it a name, which is the name of the module you are building. You can also specify the names of modules on which this module depends. These dependencies will be loaded automatically, and their typemaps, header files, etc merged with your new object's stuff. When you store the data for your object, the list of dependencies are stored with it, so that another module depending on your needn't know on exactly which modules yours depends.

For example:

  Gtk2 depends on Glib

  Gnome2::Canvas depends on Gtk2

  ExtUtils::Depends->new ('Gnome2::Canvas', 'Gtk2');
     this command automatically brings in all the stuff needed
     for Glib, since Gtk2 depends on it.

When the configuration information is saved, it also includes a class method called "Inline", inheritable by your module. This allows you in your module to simply say at the top:

  package Mymod;
  use parent 'Mymod::Install::Files'; # to inherit 'Inline' method

And users of "Mymod" who want to write inline code (using Inline) will simply be able to write:

  use Inline with => 'Mymod';

And all the necessary header files, defines, and libraries will be added for them.

The "Mymod::Install::Files" will also implement a "deps" method, which will return a list of any modules that "Mymod" depends on - you will not normally need to use this:

  require Mymod::Install::Files;
  @deps = Mymod::Install::Files->deps;

METHODS

$object = ExtUtils::Depends->new($name, @deps)
    Create a new depends object named $name. Any modules listed in @deps (which may be empty) are added as dependencies and their dependency information is loaded. An exception is raised if any dependency information cannot be loaded.

$depends->add_deps (@deps)
    Add modules listed in @deps as dependencies.

(hashes) = $depends->get_deps
    Fetch information on the dependencies of $depends as a hash of hashes, which are dependency information indexed by module name. See "load".

$depends->set_inc (@newinc)
    Add strings to the includes or cflags variables.

$depends->set_libs (@newlibs)
    Add strings to the libs (linker flags) variable.

$depends->add_pm (%pm_files)
    Add files to the hash to be passed through ExtUtils::WriteMakefile's PM key.

$depends->add_xs (@xs_files)
    Add xs files to be compiled.

$depends->add_c (@c_files)
    Add C files to be compiled.

$depends->add_typemaps (@typemaps)
    Add typemap files to be used and installed.

$depends->add_headers (list)
    No-op, for backward compatibility.

$depends->install (@files)
    Install @files to the data directory for $depends.

    This actually works by adding them to the hash of pm files that gets passed through WriteMakefile's PM key.

$depends->save_config ($filename)
    Save the important information from $depends to $filename, and set it up to be installed as name::Install::Files.

    Note: the actual value of $filename is unimportant so long as it doesn't clash with any other local files. It will be installed as name::Install::Files.

hash = $depends->get_makefile_vars
    Return the information in $depends in a format digestible by WriteMakefile.

    This sets at least the following keys:

            INC
            LIBS
            TYPEMAPS
            PM

    And these if there is data to fill them:

            clean
            OBJECT
            XS

hashref = ExtUtils::Depends::load (name)
    Load and return dependency information for name. Croaks if no such information can be found. The information is returned as an anonymous hash containing these keys:

    instpath
        The absolute path to the data install directory for this module.

    typemaps
        List of absolute pathnames for this module's typemap files.

    inc CFLAGS string for this module.

    libs
        LIBS string for this module.

    deps
        List of modules on which this one depends. This key will not exist when loading files created by old versions of ExtUtils::Depends.

    If you want to make module name support this, you must provide a module name::Install::Files, which on loading will implement the following class methods:

      $hashref = name::Install::Files->Inline('C');
      # hash to contain any necessary TYPEMAPS (array-ref), LIBS, INC
      @deps = name::Install::Files->deps;
      # any modules on which "name" depends

    An easy way to achieve this is to use the method "$depends->save_config ($filename)", but your package may have different facilities already.

$depends->load_deps
    Load $depends dependencies, by calling "load" on each dependency module. This is usually done for you, and should only be needed if you want to call "get_deps" after calling "add_deps" manually.

SUPPORT

  Bugs/Feature Requests
Version 0.2 discards some of the more esoteric features provided by the older versions. As they were completely undocumented, and this module has yet to reach 1.0, this may not exactly be a bug.

This module is tightly coupled to the ExtUtils::MakeMaker architecture.

You can submit new bugs/feature requests by using one of two bug trackers (below).

CPAN Request Tracker
    You can submit bugs/feature requests via the web by going to <https://rt.cpan.org/Public/Bug/Report.html?Queue=ExtUtils-Depends> (requires PAUSE ID or Bitcard), or by sending an e-mail to "bug-ExtUtils-Depends at rt.cpan.org".

Gnome.org Bugtracker
    Report bugs/feature requests to 'perl-extutils-depends' (requires login) <https://gitlab.gnome.org/GNOME/perl-extutils-depends/-/issues/>

Patches that implement new features with test cases, and/or test cases that exercise existing bugs are always welcome.

The Gtk-Perl support forum is at <https://discourse.gnome.org/tags/c/platform/language-bindings/11/perl>

  Source Code
The source code to ExtUtils::Depends is available at the Gnome.org Git repo (<https://gitlab.gnome.org/GNOME/perl-extutils-depends>). Create your own copy of the Git repo with:

  git clone git://git.gnome.org/perl-ExtUtils-Depends (Git protocol)
  git clone https://git.gnome.org/browse/perl-ExtUtils-Depends/ (HTTPS)

SEE ALSO
ExtUtils::MakeMaker.

AUTHOR
Paolo Molaro <lupus at debian dot org> wrote the original version for Gtk-Perl. muppet <scott at asofyet dot org> rewrote the innards for version 0.2, borrowing liberally from Paolo's code.

MAINTAINER
The Gtk2 project, <http://gtk2-perl.sf.net>/"gtk-perl-list at gnome dot org".

LICENSE
This library is free software; you may redistribute it and/or modify it under the same terms as Perl itself.