NAME

Module::Build::Using::PkgConfig - extend Module::Build to more easily use platform libraries provided by pkg-config

SYNOPSIS

In Build.PL:

   use Module::Build::Using::PkgConfig;

   my $build = Module::Build::Using::PkgConfig->new(
      module_name => "Module::Here",
      ... # other arguments as per Module::Build
   );

   # A platform library provided by pkg-config
   $build->use_pkgconfig( "libfoo" );

   # We need at least a given version
   $build->use_pkgconfig( "libbar",
      atleast_version => "0.5",
   );

   # A platform librariy that's also wrapped as an Alien module
   $build->use_pkgconfig( "libsplot",
      atleast_version => "1.0",
      alien           => "Alien::libsplot",
      alien_version   => "0.05", # Alien::libsplot 0.05 provides libsplot v1.0
   );

   $build->create_build_script;

DESCRIPTION

This subclass of Module::Build provides some handy methods to assist the Build.PL script of XS-based module distributions that make use of platform libraries managed by pkg-config.

As well as supporting libraries installed on a platform-wide basis and thus visible to pkg-config itself, this subclass also assists with Alien::-based wrappers of these system libraries, allowing them to be dynamically installed at build time if the platform does not provide them.

RPATH generation

This module also provides some helper code to generate the required RPATH arguments needed to link against the libraries found by inspecting the extra_linker_flags. This attempts to duplicate the same logic performed by libtool when it would link a C program or library, as we don't get to use its code when linking dynamic libraries for Perl.

PROPERTIES

no_late_aliens => BOOL

If true, applies the no_late_alien option to every use of use_pkgconfig that specifies an Alien module.

METHODS

use_pkgconfig

   $build->use_pkgconfig( $modname, ... )

Requires the given pkg-config module of the given version, and extends the compiler and linker arguments sufficient to build from it.

Takes the following named options:

atleast_version => $modver

If given, the pkg-config module is required to be at least the given version. If unspecified, then any version is considered sufficient.

alien => $alien

If given and the pkg-config module does not exist, try to use the given Alien:: module to provide it instead.

If this module is not yet available and the no_late_alien option is not true, the Alien module is added to the requires dynamic dependencies and checked again at build action time.

no_late_alien => BOOL

If true, suppresses the dynamic requires feature of Alien modules described above.

alien_version => $version

If the Alien:: module is not available, gives the module verison of it that will be required to provide the pkg-config module of the required version. This gets added to requires.

If neither the pkg-config module and no Alien:: module was requested (or none was found and no_late_alien was set), this method dies with an OS unsupported message, which is usually what is required for a Build.PL script.

try_pkconfig

   $ok = $build->try_pkconfig( $modname, ... )

Boolean-returning version of "use_pkgconfig". If successful, returns true. If it fails it returns false rather than dying, allowing the Build.PL script to take alternative action.

pkgconfig_atleast_version

   $ok = $build->pkgconfig_atleast_version( $modname, $modver )

Returns true if the pkg-config module name exists and has at least the given version.

add_cflags_libs_from_pkgconfig

   $build->add_cflags_libs_from_pkgconfig( $modname )

Extend the extra_compiler_flags and extra_linker_flags arguments from the --cflags and --libs from the given pkg-config module name.

alien_atleast_version

   $ok = $build->alien_atleast_version( $alien, $modver )

Returns true if the given Alien:: module provides a pkg-config module version at least the given version.

add_cflags_libs_from_alien

   $build->add_cflags_libs_from_alien( $alien )

Extend the extra_compiler_flags and extra_linker_flags arguments from the --cflags and --libs from the given Alien:: module name.

use_late_alien

   $ok = $build->use_late_alien( $alien, ... )

Adds an Alien module directly to the requires hash, and makes a note to use its cflags and libraries later at build time.

Normally this method would not be necessary as it is automatically called from use_pkgconfig if required, but one use-case may be to provide a final last-ditch attempt after trying some other possible attempts, after an earlier call to use_pkgconfig with no_late_alien set.

push_extra_compiler_flags

   $build->push_extra_compiler_flags( @flags )

Appends more values onto the extra_compiler_flags.

push_extra_linker_flags

   $build->push_extra_linker_flags( @flags )

Appends more values onto the extra_linker_flags.

TODO

  • Consider a quiet option to suppress verbose printing

  • Consider defining a constructor argument, perhaps build_requires_pkgconfig, to neaten the common case of simple requirements.

  • Consider futher stealing the various helper methods from ExtUtils::CChecker and possibly splitting this class into a lower "C-using XS modules" and higher-level pkg-config+Alien layer.

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>