NAME

       deprecate - Perl pragma for deprecating the inclusion of a module in core

SYNOPSIS

           use deprecate;  # warn about future absence if loaded from core

DESCRIPTION

       This pragma simplifies the maintenance of dual-life modules that will no longer be
       included in the Perl core in a future Perl release, but are still included currently.

       The purpose of the pragma is to alert users to the status of such a module by issuing a
       warning that encourages them to install the module from CPAN, so that a future upgrade to
       a perl which omits the module will not break their code.

       This warning will only be issued if the module was loaded from a core library directory,
       which allows the "use deprecate" line to be included in the CPAN version of the module.
       Because the pragma remains silent when the module is run from a non-core library
       directory, the pragma call does not need to be patched into or out of either the core or
       CPAN version of the module. The exact same code can be shipped for either purpose.

   Important Caveat
       Note that when a module installs from CPAN to a core library directory rather than the
       site library directories, the user gains no protection from having installed it.

       At the same time, this pragma cannot detect when such a module has installed from CPAN to
       the core library, and so it would endlessly and uselessly exhort the user to upgrade.

       Therefore modules that can install from CPAN to the core library must make sure not to
       call this pragma when they have done so. Generally this means that the exact logic from
       the installer must be mirrored inside the module. E.g.:

           # Makefile.PL
           WriteMakefile(
               # ...
               INSTALLDIRS => ( "$]" >= 5.011 ? 'site' : 'perl' ),
           );

           # lib/Foo/Bar.pm
           use if "$]" >= 5.011, 'deprecate';

       (The above example shows the most important case of this: when the target is a Perl older
       than 5.12 (where the core library directories take precedence over the site library
       directories) and the module being installed was included in core in that Perl version.
       Under those circumstances, an upgrade of the module from CPAN is only possible by
       installing to the core library.)

EXPORT

       None by default.  The only method is "import", called by "use deprecate;".

SEE ALSO

       First example to "use deprecate;" was Switch.

AUTHOR

       Original version by Nicholas Clark

COPYRIGHT AND LICENSE

       Copyright (C) 2009, 2011

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself, either Perl version 5.10.0 or, at your option, any later version of
       Perl 5 you may have available.