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PROGRAM:

NAME

PkgConfig - Pure-Perl Core-Only replacement for pkg-config

SYNOPSIS

As a replacement for "pkg-config"
$ ppkg-config --libs --cflags --static gio-2.0

#outputs (lines artificially broken up for readability):
# -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include
# -pthread -lgio-2.0 -lz -lresolv -lgobject-2.0
# -lgmodule-2.0 -ldl -lgthread-2.0 -pthread -lrt -lglib-2.0

"pkg-config.pl" can be used as an alias for "ppkg-config" on platforms that support it.
It can also be installed as "pkg-config" though this is not recomended if your system has
a native "pkg-config".

Compare to:
$ pkg-config --libs --cflags --static gio-2.0

#outputs ( "" ):
# -pthread -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include
# -pthread -lgio-2.0 -lz -lresolv -lgobject-2.0 -lgmodule-2.0
# -ldl -lgthread-2.0 -lrt -lglib-2.0

From another Perl module
use PkgConfig;

my $o = PkgConfig->find('gio');
if($o->errmsg) {
#handle error
} else {
my $prefix = $o->get_var('prefix');
my @cflags = $o->get_cflags;
my @ldflags = $o->get_ldflags;
}

DESCRIPTION

"PkgConfig" provides a pure-perl, core-only replacement for the "pkg-config" utility.

This is not a description of the uses of "pkg-config" but rather a description of the
differences between the C version and the Perl one.

While "pkg-config" is a compiled binary linked with glib, the pure-perl version has no
such requirement, and will run wherever Perl ( >= 5.6 ) does.

The main supported options are the common "--libs", "--cflags", "--static", "--exists" and
"--modversion".

SCRIPT OPTIONS
USAGE

<packagename1 pkgname2..> [ --options ]

ARGUMENTS

By default, a library name must be supplied unless one of --version, or --real-version is
specified.

The output should normally be suitable for passing to your favorite compiler.

--libs

(Also) print linker flags. Dependencies are traverse in order. Top-level dependencies will
appear earlier in the command line than bottom-level dependencies.

--libs-only-L

Prints -L/-R part of "--libs". It defines library search path but without libraries to
link with.

--libs-only-l

Prints the -l part of "--libs".

--libs-only-other

Prints the part of "--libs" not covered by "--libs-only-L" and "--libs-only-l", such as
"--pthread".

--list-all

List all know packages.

--cflags

(Also) print compiler and C preprocessor flags.

--cflags-only-I

Prints the -I part of "--cflags"

--cflags-only-other

Prints the parts of "--cflags" not covered by "--cflags-only-I".

--modversion

Print the version of a given package.

--static

Use extra dependencies and libraries if linking against a static version of the requested
library

--exists

Return success (0) if the package exists in the search path.

--with-path=PATH

Prepend "PATH" to the list of search paths containing ".pc" files.

This option can be specified multiple times with different paths, and they will all be
added.

--env-only

Using this option, only paths specified in "PKG_CONFIG_PATH" are recognized and any hard-
coded defaults are ignored.

--guess-paths

Invoke "gcc" and "ld" to determine default linker and include paths. Default paths will be
excluded from explicit -L and -I flags.

--define-variable=VARIABLE=VALUE

Define a variable, overriding any such variable definition in the .pc file, and allowing
your value to interpolate with subsequent uses.

--variable=VARIABLE

This returns the value of a variable defined in a package's .pc file.

--print-variables

Print all defined variables found in the .pc files.

--version

The target version of "pkg-config" emulated by this script

--real-version

The actual version of this script

--debug

Print debugging information

--silence-errors

Turn off errors. This is the default for non-libs/cflag/modversion arguments

--print-errors

Print errors to STDERR and takes precedence over "--silence-errors"

--short-errors

Ignored, but recognized for compatibility.

--errors-to-stdout

Print errors to STDOUT and takes precedence over "--print-errors"

ENVIRONMENT

the "PKG_CONFIG_PATH" and "PKG_CONFIG_LIBDIR" variables are honored and used as a colon-
delimited (semicolon-delimited on Windows) list of directories with contain ".pc" files.

Other environment variables recongized by both "pkg-config" and PkgConfig include:

PKG_CONFIG_ALLOW_SYSTEM_CFLAGS
PKG_CONFIG_ALLOW_SYSTEM_LIBS

If Win32API::Registry is installed, on Windows (but not Cygwin) PkgConfig will also
consult these registry keys. The names are ignored, but the values are paths containing
".pc" files.

HKEY_CURRENT_USER\Software\pkgconfig\PKG_CONFIG_PATH
HKEY_LOCAL_MACHINE\Software\pkgconfig\PKG_CONFIG_PATH

Registry support should be considered somewhat experimental, subject to change in the
future, though not without good reason. The rationale for this caveat is that this
feature is documented in several places, but I have yet to find a working version that
implements this feature.

MODULE OPTIONS
PkgConfig->find

my $result = PkgConfig->find($libary, %options);

Find a library and return a result object. $library can be either a single name of a
library, or a reference to an array of library names

The options are in the form of hash keys and values, and the following are recognized:

"search_path"
"search_path_override"
Prepend search paths in addition to the paths specified in $ENV{PKG_CONFIG_PATH} The
value is an array reference.

the "_override" variant ignores defaults (like "PKG_CONFIG_PATH").

"file_path"
Specifies the full path of the of the .pc file that you wish to load. It does not
need to be in the search path (although any dependencies will need to be). Useful if
you know the full path of the exact .pc file that you want.

"exclude_cflags"
"exclude_ldflags"
"exclude_cflags_override"
"exclude_ldflags_override"
Some ".pc" files specify default compiler and linker search paths, e.g.
"-I/usr/include -L/usr/lib". Specifying them on the command line can be problematic as
it drastically changes the search order.

The above options will either append or replace the options which are excluded and
filtered.

The default excluded linker and compiler options can be obtained via
@PkgConfig::DEFAULT_EXCLUDE_LFLAGS and @PkgConfig::DEFAULT_EXCLUDE_CFLAGS,
respectively.

"static"
Also specify static libraries.

"no_recurse"
Do not recurse dependencies. This is useful for just doing version checks.

"VARS"
Define a hashref of variables to override any variable definitions within the .pc
files. This is equivalent to the "--define-variable" command-line option.

A "PkgConfig" object is returned and may be queried about the results:

$o->errmsg

An error message, if any. This is a string and indicates an error.

$o->pkg_exists

Boolean value, true if the package exists.

$o->pkg_version

The version of the package

$o->get_cflags

$o->get_ldflags

Returns compiler and linker flags, respectively.

In list context, these methods return a list with each argument split on unescaped spaces.

In list context returns a list of compiler and linker flags, respectively.

In scalar context returns a string of compiler and linker flags with spaces and quotes
escaped correctly.

$o->get_var($name)

Get the variable with the given name.

PkgConfig->Guess

This is a class method, and will replace the hard-coded default linker and include paths
with those discovered by invoking ld(1) and cpp(1).

Currently this only works with GCC-supplied "ld" and GNU "ld".

INSTALL
The "Makefile.PL" that comes with "PkgConfig" can take one or more "--script" options to
change of the name of the script or scripts that are installed.

--script ppkg-config
This is the default and works on all platforms

--script pkg-config.pl
This is installed by default on all platforms except for Windows, where the .pl may
confuse the shell and cause the script to be opened in a text editor.

--script pkg-config
This is the default name of the real "pkg-config" and so you have to specifically
enable it if you want it.

--script none
Don't install any scripts.

Example, install all script names:

% perl Makefile.PL --script ppkg-config --script pkg-config.pl --script pkg-config

Example, don't install any scripts:

% perl Makefile.PL --script none

You can also set the environment variable PERL_PKG_CONFIG_SCRIPTS to the desired --script
value (separating each script name with a comma ",") to ensure that upgrades of PkgConfig
do the same.

CAVEATS
On Strawberry Perl "ppkg-config" acts like Strawberry is the system. This means that

· The .pc files that are bundled with Strawberry are searched by default.

· The Strawberry include and lib directories are used to compute the exclusion lists.

As of Strawberry 5.20.0.1 PkgConfig is bundled with Strawberry and "pkg-config" is
installed by default (in addition to "ppkg-config", though the "ppkg-config" alias is NOT
bundled with Strawberry itself).

For details on how to patch the .pc files bundled with older Strawberries, see the
"README.win32" that comes with this Distribution.

BUGS
The order of the flags is not exactly matching to that of "pkg-config". From my own
observation, it seems this module does a better job, but I might be wrong.

Unlike "pkg-config", the scripts "--exists" function will return nonzero if a package or
any of its dependencies are missing. This differs from the behavior of "pkg-config" which
will just check for the definition of the package itself (without dependencies).

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