Mostly as a test of Perl's namespace munging, I wanted to share
functions
and symbols ($var etc) between modules.
I came up with the following implemetation.
In a.pl you can say
---------
use b;
use shared qw( $config =&hello );
sub hello
{
print "Hello World\n";
}
---------
and in 'b.pm' you can say
---------
use shared qw( $config &hello );
---------
Now, '$config' imports '$shared::config' into the local namespace
so all code and any modules which declares 'use shared qw($config)' can
use $config as a package local variable and see the same data.
AND.
use shared qw( =&hello )
saves 'package::hello' in a hash in 'shared::export_map'. Later
when a module calls
use shared qw( &hello )
it exports filter::hello to the local package. The first time
'hello' is called, the filter::autoload uses the 'export_map' to export
'hello' to the calling package and then uses goto to make sure the
function
gets called. (package::hello can't be exported directly, because it gets
imported in 'b' before it gets exported from 'main' due to the order of
execution of use/import() )
It works well, but the obvious question is, has it been done already?
Cheers.
David
[bits/ideas stolen from Exporter::Heavy.pm]
----------------------- snip --------------------------
package shared;
require 5.001;
use strict;
use warnings;
use Exporter;
use Carp;
use vars qw( @ISA @EXPORTS $AUTOLOAD %export_map );
@ISA = qw( Exporter );
sub AUTOLOAD{
no strict 'refs';
# Perform a lookup for an exported function. If found
# export it to the calling namespace and go to it, otherwise
# croak.
if( exists $export_map{$AUTOLOAD} ) {
my $pkg = caller;
my $i = $export_map{$AUTOLOAD};
*{"$pkg::$i->[1]"} = \&{$export_map{$AUTOLOAD}->[2]};
goto &{$export_map{$AUTOLOAD}->[2]}
}
Carp::croak "Undefined subroutine &".$AUTOLOAD;
}
sub import {
my @exports = @_[ 1 .. $#_ ];
my ( $type, $sym, $ssym );
my $pkg = caller;
no strict 'refs';
for $sym (@exports) {
# Handle shared export. (function local to a package and shared
out,
# rather than shared import from 'shared::' namespace)
if( $sym =~ /^=(\W)?(.+)$/ ) {
Carp::croak "Symbol already shared from
$export_map{$2}->[2]"
if exists $export_map{$2};
$export_map{$2} = [ $1, $2, "${pkg}::${2}" ];
$export_map{"shared::$2"} = [ $1, $2, "${pkg}::${2}" ];
next;
}
# Install symbol in 'pkg' to refer to symbol in 'shared::'
namespace
# This will fail for functions, resulting in a call to
'AUTOLOAD' above.
$ssym = "shared::${2}" if $sym =~ /^(\W)?(.+)$/;
( *{"${pkg}::$sym"} = \&{"$sym"}, next )
unless $sym =~ s/^(\W)//;
$type = $1;
*{"${pkg}::$sym"} =
$type eq '&' ? \&{"$ssym"}
: $type eq '$' ? \${"$ssym"}
: $type eq '@' ? [EMAIL PROTECTED]"$ssym"}
: $type eq '%' ? \%{"$ssym"}
: $type eq '*' ? *{"$ssym"}
: undef;
}
}
1;
----------------------- snip --------------------------
Regards,
David le Blanc
--
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