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Glib::version(3pm)    User Contributed Perl Documentation   Glib::version(3pm)

NAME
       Glib::version -	Library Versioning Utilities

SYNOPSIS
	 # require at least version 1.021 of the Glib module
	 use Glib '1.021';

	 # g_set_application_name() was introduced in GLib 2.2.0, and
	 # first supported by version 1.040 of the Glib Perl module.
	 if ($Glib::VERSION >= 1.040 and Glib->CHECK_VERSION (2,2,0)) {
	    Glib::set_application_name ('My Cool Program');
	 }

DESCRIPTION
       Both the Glib module and the GLib C library are works-in-progress, and
       their interfaces grow over time.	 As more features are added to each,
       and your code uses those new features, you will introduce version-
       specific dependencies, and naturally, you'll want to be able to code
       around them.  Enter the versioning API.

       For simple Perl modules, a single version number is sufficient;
       however, Glib is a binding to another software library, and this
       introduces some complexity.  We have three versions that fully specify
       the API available to you.

       Perl Bindings Version
	   Perl modules use a version number, and Glib is no exception.
	   $Glib::VERSION is the version of the current Glib module.  By ad
	   hoc convention, gtk2-perl modules generally use version numbers in
	   the form x.yyz, where even yy values denote stable releases and z
	   is a patchlevel.

	      $Glib::VERSION
	      use Glib 1.040; # require at least version 1.040

       Compile-time ("Bound") Library Version
	   This is the version of the GLib C library that was available when
	   the Perl module was compiled and installed.	These version
	   constants are equivalent to the version macros provided in the GLib
	   C headers.  GLib uses a major.minor.micro convention, where even
	   minor versions are stable.  (gtk2-perl does not officially support
	   unstable versions.)

	      Glib::MAJOR_VERSION
	      Glib::MINOR_VERSION
	      Glib::MICRO_VERSION
	      Glib->CHECK_VERSION($maj,$min,$mic)

       Run-time ("Linked") Library Version
	   This is the version of the GLib C library that is available at run
	   time; it may be newer than the compile-time version, but should
	   never be older.  These are equivalent to the version variables
	   exported by the GLib C library.

	      Glib::major_version
	      Glib::minor_version
	      Glib::micro_version

   Which one do I use when?
       Where do you use which version?	It depends entirely on what you're
       doing.  Let's explain by example:

       o Use the Perl module version for bindings support issues
	   You need to register a new enum for use as the type of an object
	   property.  This is something you can do with all versions of the
	   underlying C library, but which wasn't supported in the Glib Perl
	   module until $Glib::VERSION >= 1.040.

       o Use the bound version for library features
	   You want to call Glib::set_application_name to set a human-readable
	   name for your application (which is used by various parts of Gtk2
	   and Gnome2).	 g_set_application_name() (the underlying C function)
	   was added in version 2.2.0 of glib, and support for it was
	   introduced into the Glib Perl module in Glib version 1.040.
	   However, you can build the Perl module against any stable 2.x.x
	   version of glib, so you might not have that function available even
	   if your Glib module is new enough!
	     Thus, you need to check two things to see if the this function is
	   available:

	      if ($Glib::VERSION >= 1.040 && Glib->CHECK_VERSION (2,2,0)) {
		  # it's available, and we can call it!
		  Glib::set_application_name ('My Cool Application');
	      }

	   Now what happens if you installed the Perl module when your system
	   had glib 2.0.6, and you upgraded glib to 2.4.1?  Wouldn't
	   g_set_application_name() be available?  Well, it's there, under the
	   hood, but the bindings were compiled when it wasn't there, so you
	   won't be able to call it!  That's why we check the "bound" or
	   compile-time version.  By the way, to enable support for the new
	   function, you'd need to reinstall (or upgrade) the Perl module.

       o Use the linked version for runtime work-arounds
	   Suppose there's a function whose API did not change, but whose
	   implementation had a bug in one version that was fixed in another
	   version.  To determine whether you need to apply a workaround, you
	   would check the version that is actually being used at runtime.

	      if (Glib::major_version == 2 &&
		  Glib::minor_version == 2 &&
		  Glib::micro_version == 1) {
		 # work around bug that exists only in glib 2.2.1.
	      }

	   In practice, such situations are very rare.

METHODS
   boolean = Glib->CHECK_VERSION ($required_major, $required_minor,
       $required_micro)
       ·   $required_major (integer)

       ·   $required_minor (integer)

       ·   $required_micro (integer)

       Provides a mechanism for checking the version information that Glib was
       compiled against. Essentially equvilent to the macro
       GLIB_CHECK_VERSION.

   (MAJOR, MINOR, MICRO) = Glib->GET_VERSION_INFO
       Shorthand to fetch as a list the glib version for which Glib was
       compiled.  See "Glib::MAJOR_VERSION", etc.

   integer = Glib::MAJOR_VERSION
       Provides access to the version information that Glib was compiled
       against.	 Essentially equivalent to the #define's GLIB_MAJOR_VERSION.

   integer = Glib::MICRO_VERSION
       Provides access to the version information that Glib was compiled
       against.	 Essentially equivalent to the #define's GLIB_MICRO_VERSION.

   integer = Glib::MINOR_VERSION
       Provides access to the version information that Glib was compiled
       against.	 Essentially equivalent to the #define's GLIB_MINOR_VERSION.

   integer = Glib::major_version
       Provides access to the version information that Glib is linked against.
       Essentially equivalent to the global variable glib_major_version.

   integer = Glib::micro_version
       Provides access to the version information that Glib is linked against.
       Essentially equivalent to the global variable glib_micro_version.

   integer = Glib::minor_version
       Provides access to the version information that Glib is linked against.
       Essentially equivalent to the global variable glib_minor_version.

SEE ALSO
       Glib

COPYRIGHT
       Copyright (C) 2003-2011 by the gtk2-perl team.

       This software is licensed under the LGPL.  See Glib for a full notice.

perl v5.18.1			  2014-01-08		    Glib::version(3pm)
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