update: the most recent version of this module is available at
use base [ MODULE => version ]; (a change to base.pm).
i like to use base 'CGI::Application' quite often, but I also want at least CGI::Application::VERSION 2.1, and I dont like saying use CGI::Application 2.1, and since I don't wanna change the behaviour of base as it stands, I propose passing use base a {}, like
(readmore follows ~ code and most of the questions are after)
=head1 NAME
base - Establish IS-A relationship with base class at compile time
=head1 SYNOPSIS
package Baz;
use base qw(Foo Bar);
## new usage allowed by podmaster, allows for require MODULE versi
+onnumber;
package Baz;
use base { Foo => 1, 'Foo::Bar' => 2}; ## need quotes
use base \%{{ BARE::WORD => 2}}; ## only works like this
=head1 DESCRIPTION
Roughly similar in effect to
BEGIN {
require Foo;
require Bar;
push @ISA, qw(Foo Bar);
}
Will also initialize the %FIELDS hash if one of the base classes has
it. Multiple inheritance of %FIELDS is not supported. The 'base'
pragma will croak if multiple base classes have a %FIELDS hash. See
L<fields> for a description of this feature.
When strict 'vars' is in scope I<base> also let you assign to @ISA
without having to declare @ISA with the 'vars' pragma first.
If any of the base classes are not loaded yet, I<base> silently
C<require>s them. Whether to C<require> a base class package is
determined by the absence of a global $VERSION in the base package.
If $VERSION is not detected even after loading it, <base> will
define $VERSION in the base package, setting it to the string
C<-1, set by base.pm>.
The new feature of this module, allows for version checking via
use base { 'MODULE' => 33 }; # version 33
which is roughly equivalent to
use MODULE 33;
use base 'MODULE';
and will C<croak> much like C<perl -MMODULE=33 -e 1>
if version 33 of MODULE is not available
=head1 HISTORY
This module was introduced with Perl 5.004_04.
=head1 SEE ALSO
L<fields>
=cut
package base;
use 5.006_001;
our $VERSION = "1.02";
sub import {
my $class = shift;
my $fields_base;
my $pkg = caller(0);
my @bases = @_; ##podmaster - cause i don't wanna modify @bases
my %BASV=(); ##podmaster
if(ref $bases[0] eq 'HASH') { ##podmaster
%BASV = %{$bases[0]};
@bases = keys %BASV;
}
foreach my $base (@bases) { ##podmaster
next if $pkg->isa($base);
push @{"$pkg\::ISA"}, $base;
my $vglob;
unless (${*{"$base\::VERSION"}{SCALAR}}) {
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 (%{"$base\::"}) {
require Carp;
Carp::croak("Base class package \"$base\" is empty.\n",
"\t(Perhaps you need to 'use' the module ",
"which defines that package first.)");
}
${"$base\::VERSION"} = "-1, set by base.pm"
unless ${*{"$base\::VERSION"}{SCALAR}};
}
##podmaster - allows for use base { module => versionnumber }
if(%BASV and exists $BASV{$base}
and $BASV{$base} > ${"${base}::VERSION"}) { ## wanted > av
+ailable
require Carp;
Carp::croak("$base version $BASV{$base} required--this is only
+ version "
.${"${base}::VERSION"});
}
# A simple test like (defined %{"$base\::FIELDS"}) will
# sometimes produce typo warnings because it would create
# the hash if it was not present before.
my $fglob;
if ($fglob = ${"$base\::"}{"FIELDS"} and *$fglob{HASH}) {
if ($fields_base) {
require Carp;
Carp::croak("Can't multiply inherit %FIELDS");
} else {
$fields_base = $base;
}
}
}
if ($fields_base) {
require fields;
fields::inherit($pkg, $fields_base);
}
}
1;
Ideas comments suggestions are all welcome. I don't know if this has been brought up before (looked, didn't find much), and I wasn't able to check if the latest base.pm does this, and mine don't (5.6) , so ... feedback!
btw, why doesn't the power of => kick in "use base { FOO::BAR => 1 };"?
P.S ~ could I get into core $^O? ;)
update ( Mon Jun 10 07:19:10 2002 ): *sigh* it appears the problem usage was with an unless statement that I had changed to if, but somehow reverted to unless again. It's been fixed now, and I sent this thing to perl5-porters (in preparation for which, i rewrote it, along with a test).
#!/usr/bin/perl -w
package GENERIC;
use lib qw(.);
use strict;
BEGIN {
use base 'CGI::Application'; # regular usage
use base { 'CGI::Application' => 2.1 }; # new usage
use base { # do the switch'a'roo to see an err message
'DBI' => 1,
# 'DBI' => 16,
};
}
sub setup {
my $self = shift;
$self->start_mode('hi');
$self->mode_param('op');
$self->run_modes(
hi => sub {" hi ".join(' ',caller())},
AUTOLOAD => sub {" hello ".join(' ',caller())},
);
}
package main;
my $DE_GENERIC = GENERIC->new();
$DE_GENERIC->run();
