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.\" ========================================================================
.\"
.IX Title "Module::Build::Using::PkgConfig 3pm"
.TH Module::Build::Using::PkgConfig 3pm "2022-11-30" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
"Module::Build::Using::PkgConfig" \- extend "Module::Build" to more easily use platform libraries provided by pkg\-config
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
In \fIBuild.PL\fR:
.PP
.Vb 1
\&   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\*(Aqs 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;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This subclass of Module::Build provides some handy methods to assist the
\&\fIBuild.PL\fR script of XS-based module distributions that make use of platform
libraries managed by \fIpkg-config\fR.
.PP
As well as supporting libraries installed on a platform-wide basis and thus
visible to \fIpkg-config\fR itself, this subclass also assists with
\&\f(CW\*(C`Alien::\*(C'\fR\-based wrappers of these system libraries, allowing them to be
dynamically installed at build time if the platform does not provide them.
.SS "\s-1RPATH\s0 generation"
.IX Subsection "RPATH generation"
This module also provides some helper code to generate the required \f(CW\*(C`RPATH\*(C'\fR
arguments needed to link against the libraries found by inspecting the
\&\f(CW\*(C`extra_linker_flags\*(C'\fR. This attempts to duplicate the same logic performed
by \fIlibtool\fR when it would link a C program or library, as we don't get to
use its code when linking dynamic libraries for Perl.
.SH "PROPERTIES"
.IX Header "PROPERTIES"
.IP "no_late_aliens => \s-1BOOL\s0" 4
.IX Item "no_late_aliens => BOOL"
If true, applies the \f(CW\*(C`no_late_alien\*(C'\fR option to every use of \f(CW\*(C`use_pkgconfig\*(C'\fR
that specifies an Alien module.
.SH "METHODS"
.IX Header "METHODS"
.SS "use_pkgconfig"
.IX Subsection "use_pkgconfig"
.Vb 1
\&   $build\->use_pkgconfig( $modname, ... )
.Ve
.PP
Requires the given \fIpkg-config\fR module of the given version, and extends
the compiler and linker arguments sufficient to build from it.
.PP
Takes the following named options:
.ie n .IP "atleast_version => $modver" 4
.el .IP "atleast_version => \f(CW$modver\fR" 4
.IX Item "atleast_version => $modver"
If given, the \fIpkg-config\fR module is required to be at least the given
version. If unspecified, then any version is considered sufficient.
.ie n .IP "alien => $alien" 4
.el .IP "alien => \f(CW$alien\fR" 4
.IX Item "alien => $alien"
If given and the \fIpkg-config\fR module does not exist, try to use the given
\&\f(CW\*(C`Alien::\*(C'\fR module to provide it instead.
.Sp
If this module is not yet available and the \f(CW\*(C`no_late_alien\*(C'\fR option is not
true, the Alien module is added to the \f(CW\*(C`requires\*(C'\fR dynamic dependencies and
checked again at \f(CW\*(C`build\*(C'\fR action time.
.IP "no_late_alien => \s-1BOOL\s0" 4
.IX Item "no_late_alien => BOOL"
If true, suppresses the dynamic \f(CW\*(C`requires\*(C'\fR feature of Alien modules
described above.
.ie n .IP "alien_version => $version" 4
.el .IP "alien_version => \f(CW$version\fR" 4
.IX Item "alien_version => $version"
If the \f(CW\*(C`Alien::\*(C'\fR module is not available, gives the module version of it that
will be required to provide the \fIpkg-config\fR module of the required version.
This gets added to \f(CW\*(C`requires\*(C'\fR.
.PP
If neither the \fIpkg-config\fR module and no \f(CW\*(C`Alien::\*(C'\fR module was requested (or
none was found and \f(CW\*(C`no_late_alien\*(C'\fR was set), this method dies with an
\&\f(CW\*(C`OS unsupported\*(C'\fR message, which is usually what is required for a \fIBuild.PL\fR
script.
.SS "try_pkconfig"
.IX Subsection "try_pkconfig"
.Vb 1
\&   $ok = $build\->try_pkconfig( $modname, ... )
.Ve
.PP
Boolean-returning version of \*(L"use_pkgconfig\*(R". If successful, returns true.
If it fails it returns false rather than dying, allowing the \fIBuild.PL\fR
script to take alternative action.
.SS "pkgconfig_atleast_version"
.IX Subsection "pkgconfig_atleast_version"
.Vb 1
\&   $ok = $build\->pkgconfig_atleast_version( $modname, $modver )
.Ve
.PP
Returns true if the \fIpkg-config\fR module name exists and has at least the
given version.
.SS "add_cflags_libs_from_pkgconfig"
.IX Subsection "add_cflags_libs_from_pkgconfig"
.Vb 1
\&   $build\->add_cflags_libs_from_pkgconfig( $modname )
.Ve
.PP
Extend the \f(CW\*(C`extra_compiler_flags\*(C'\fR and \f(CW\*(C`extra_linker_flags\*(C'\fR arguments from
the \f(CW\*(C`\-\-cflags\*(C'\fR and \f(CW\*(C`\-\-libs\*(C'\fR from the given \fIpkg-config\fR module name.
.SS "alien_atleast_version"
.IX Subsection "alien_atleast_version"
.Vb 1
\&   $ok = $build\->alien_atleast_version( $alien, $modver )
.Ve
.PP
Returns true if the given \f(CW\*(C`Alien::\*(C'\fR module provides a \fIpkg-config\fR module
version at least the given version.
.SS "add_cflags_libs_from_alien"
.IX Subsection "add_cflags_libs_from_alien"
.Vb 1
\&   $build\->add_cflags_libs_from_alien( $alien )
.Ve
.PP
Extend the \f(CW\*(C`extra_compiler_flags\*(C'\fR and \f(CW\*(C`extra_linker_flags\*(C'\fR arguments from
the \f(CW\*(C`\-\-cflags\*(C'\fR and \f(CW\*(C`\-\-libs\*(C'\fR from the given \f(CW\*(C`Alien::\*(C'\fR module name.
.SS "use_late_alien"
.IX Subsection "use_late_alien"
.Vb 1
\&   $ok = $build\->use_late_alien( $alien, ... )
.Ve
.PP
Adds an Alien module directly to the \f(CW\*(C`requires\*(C'\fR hash, and makes a note to use
its cflags and libraries later at build time.
.PP
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 \f(CW\*(C`use_pkgconfig\*(C'\fR with \f(CW\*(C`no_late_alien\*(C'\fR set.
.SS "push_extra_compiler_flags"
.IX Subsection "push_extra_compiler_flags"
.Vb 1
\&   $build\->push_extra_compiler_flags( @flags )
.Ve
.PP
Appends more values onto the \f(CW\*(C`extra_compiler_flags\*(C'\fR.
.SS "push_extra_linker_flags"
.IX Subsection "push_extra_linker_flags"
.Vb 1
\&   $build\->push_extra_linker_flags( @flags )
.Ve
.PP
Appends more values onto the \f(CW\*(C`extra_linker_flags\*(C'\fR.
.SH "TODO"
.IX Header "TODO"
.IP "\(bu" 4
Consider a \f(CW\*(C`quiet\*(C'\fR option to suppress verbose printing
.IP "\(bu" 4
Consider defining a constructor argument, perhaps \f(CW\*(C`build_requires_pkgconfig\*(C'\fR,
to neaten the common case of simple requirements.
.IP "\(bu" 4
Consider further stealing the various helper methods from ExtUtils::CChecker
and possibly splitting this class into a lower \*(L"C\-using \s-1XS\s0 modules\*(R" and
higher-level \fIpkg-config\fR+Alien layer.
.SH "AUTHOR"
.IX Header "AUTHOR"
Paul Evans <leonerd@leonerd.org.uk>