Question

I have a package that I just made and I have an ‘old-mode’ that basically makes it work like it worked before: importing everything into the current namespace. One of the nice things about having this as a package is that we no longer have to do that. Anyway, what I would like to do is have it so that whenever anyone does:

use Foo qw(:oldmode); 

I throw a warning that this is deprecated and that they should either import only what they need or just access functions with Foo->fun();

Any ideas on how to do this?

Answer 1

Well, as you specifically state that you want to alarm in the cases of use Mod qw<:oldmode>; This works better:

package Foo; use base qw<Exporter>; use Carp qw<carp>; ... sub import {      #if ( grep { $_ eq ':oldmode' } @_ ) { # Perl 5.8     if ( @_ ~~ ':oldmode' ) {              # Perl 5.10          carp( 'import called with :oldmode!' );     }     goto &{Exporter->can( 'import' )}; } 

Thanks to Frew, for mentioning the Perl 5.10 smart match syntax. I’m learning all the ways to work Perl 5.10 into my code.

Note: the standard way to use exporter in an import sub is to either manipulate $Exporter::ExportLevel or to call Foo->export_to_level( 1, @_ ); But I like the way above. It’s quicker and, I think, simpler.