NAME
    future - make pragmas optional

SYNOPSIS
        # require all users to have future.pm installed
        use future qw(encoding sort);
        use encoding 'iso-8859-1';
        use sort '_qsort';

        # require only users of old perl versions to have future.pm installed
        BEGIN { eval 'use future qw(warnings)' }
        use warnings "all";

DESCRIPTION
    This module is for authors which would like to use "modern" pragmas in
    their modules and scripts, but also want to remain backward-compatible
    to older versions of perl without these pragmas. Suppose you want to
    "use warnings":

        use warnings;
        # your script

    This will croak on perl 5.005_03 and older, because there is no
    "warnings.pm" for these versions. Now you could try some tricks like:

        BEGIN { eval 'use warnings' }

    but this will not work, because pragmas are often lexically scoped, so
    the warnings pragma would be only valid in the BEGIN block (or even in
    the eval block, I have not checked).

    With "future.pm" you can either write:

        use future qw(warnings);
        use warnings 'whatever';

    which would enable the warnings pragma for perl 5.6.0 and newer and make
    the pragma an no-op for older perls. If you do not want your users to
    install the "future.pm" module (after all it is a non-standard module),
    then you can write:

        BEGIN { eval 'use future qw(warnings)' }
        use warnings "whatever";

    Note that the new pragma "if" cannot do this --- if you think it can,
    then tell me and I retract this module ":-)"

AUTHOR
    Slaven Rezic <slaven.rezic@berlin.de>

COPYRIGHT
    Copyright (c) 2002 Slaven Rezic. All rights reserved. This module is
    free software; you can redistribute it and/or modify it under the same
    terms as Perl itself.

SEE ALSO
    perlmodlib(1), if(3).