# phpman > man > deprecate(3perl)

## 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.