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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.



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