[p5sagit/p5-mst-13.2.git] / lib / base.pm

=head1 NAME

base - Establish IS-A relationship with base class at compile time

=head1 SYNOPSIS

    package Baz;

    use base qw(Foo Bar);

=head1 DESCRIPTION

Roughly similar in effect to

    BEGIN {
	require Foo;
	require Bar;
	push @ISA, qw(Foo Bar);
    }

This module was introduced with Perl 5.004_04.

=head1 BUGS

Needs proper documentation!

=cut

package base;

sub import {
    my $class = shift;

    foreach my $base (@_) {
	unless (defined %{"$base\::"}) {
	    eval "require $base";
	    # Only ignore "Can't locate" errors from our eval require.
	    # Other fatal errors (syntax etc) must be reported.
	    die if $@ && $@ !~ /^Can't locate .*? at \(eval /;
	    unless (defined %{"$base\::"}) {
		require Carp;
		Carp::croak("Base class package \"$base\" is empty.\n",
			    "\t(Perhaps you need to 'use' the module ",
			    "which defines that package first.)");
	    }
	}
    }
    
    push @{caller(0) . '::ISA'}, @_;
}

1;
Commit	Line	Data
fb73857a	1	=head1 NAME
	2
	3	base - Establish IS-A relationship with base class at compile time
	4
	5	=head1 SYNOPSIS
	6
	7	package Baz;
	8
	9	use base qw(Foo Bar);
	10
	11	=head1 DESCRIPTION
	12
	13	Roughly similar in effect to
	14
	15	BEGIN {
	16	require Foo;
	17	require Bar;
	18	push @ISA, qw(Foo Bar);
	19	}
	20
	21	This module was introduced with Perl 5.004_04.
	22
	23	=head1 BUGS
	24
	25	Needs proper documentation!
	26
	27	=cut
	28
	29	package base;
	30
	31	sub import {
	32	my $class = shift;
	33
	34	foreach my $base (@_) {
	35	unless (defined %{"$base\::"}) {
	36	eval "require $base";
9b599b2a	37	# Only ignore "Can't locate" errors from our eval require.
	38	# Other fatal errors (syntax etc) must be reported.
	39	die if $@ && $@ !~ /^Can't locate .*? at \(eval /;
fb73857a	40	unless (defined %{"$base\::"}) {
	41	require Carp;
	42	Carp::croak("Base class package \"$base\" is empty.\n",
	43	"\t(Perhaps you need to 'use' the module ",
	44	"which defines that package first.)");
	45	}
	46	}
	47	}
	48
	49	push @{caller(0) . '::ISA'}, @_;
	50	}
	51
	52	1;