pragma.pm plays well with others

jjore on 2006-12-07T20:39:03

For kicks I wrote the pragma pragma which just mucks with other user pragmas. I'm not sure what good this is except that I wanted a simple API to poke at other people's pragmas. I might even upload this to CPAN just so it's handy.

package pragma;
use strict;
use warnings;

our $VERSION = ~0;

=head1 NAME

pragma - A pragma for controlling other user pragmas

=head1 DESCRIPTION

The C pragma is a module which influences other user pragmata
such as L. With Perl 5.10 you can create user pragmata and the
C pragma can modify and peek at other pragmata.

=head1 A basic example

Assume you're using the C pragma mentioned in
L. For ease, that pragma is duplicated here.

    package myint;

    use strict;
    use warnings;

    sub import {
        $^H{myint} = 1;
    }

    sub unimport {
        $^H{myint} = 0;
    }

    sub value {
        my $level = shift // 0;
        my $hinthash = (caller($level))[10];
        return $hinthash->{myint};
    }

    1;

Other code might casually wish to dip into C:

    no pragma 'myint';      # delete $^H{myint}
    use pragma myint => 42; # $^H{myint} = 42

    print pragma->peek( 'myint' ); # prints '42'

=cut

=head1 CLASS METHODS

=over

=item C<< use pragma PRAGMA => VALUE >>

=item C<< pragma->import( PRAGMA => VALUE ) >>

=item C<< pragma->poke( PRAGMA => VALUE ) >>

Sets C's value to C.

=cut

sub import {
    my ( undef, $pragma, $value ) = @_;

    $^H{$pragma} = $value;
    return;
}
*poke = \&import;

=item C<< no pragma PRAGMA >>

=item C<< pragma->unimport( PRAGMA ) >>

Unsets C.

=cut

sub unimport {
    my ( undef, $pragma ) = @_;

    delete $^H{$pragma} if exists $^H{$pragma};
    return;
}

=item C<< pragma->peek( PRAGMA ) >>

Returns the current value of C.

=cut

sub peek {
    my ( undef, $pragma ) = @_;

    return $^H{$pragma};
}

=back

=head1 SUBCLASSING

All methods may be subclassed.

=cut

q[And I don't think an entire stallion of horses, or a tank, could stop you two from getting married.];