Re (tilly) 2: Best/possible ways to dynamically use modules

You can always fool around with a goto:

{
  my %is_imported;

  sub lazy_use {
    my ($class, @args) = @_;
    unless ($is_imported{"$class @args"}++) {
      my $file = $class;
      $file =~ s-::-/-g;
      $file .= ".pm";
      require $file;

      my $importer = UNIVERSAL::can($class, "import");
      goto &$importer if defined $importer;
    }
  }
}
[download]

and now you can issue many calls to the lazy_use routine and it will parse once and import once. In fact this routine could be exported to other namespaces and should work correctly.

Comment on Re (tilly) 2: Best/possible ways to dynamically use modules Download Code

Replies are listed 'Best First'.
Re: Re (tilly) 2: Best/possible ways to dynamically use modules by perrin (Chancellor) on Dec 18, 2001 at 21:43 UTC
Is there any reason to use that goto instead of simply calling the sub, or are you just being perverse?	[reply]
Re (tilly) 4: Best/possible ways to dynamically use modules by tilly (Archbishop) on Dec 18, 2001 at 21:52 UTC
There is an extremely good reason to use it. Most import routines look at caller to figure out where they are exporting stuff to. If you want the function that I gave to be usefully called from multiple packages (and it is complicated enough that I would), then that function to not appear on the call-stack. The alternative would be to interact with the import to let it know where to export to. Unfortunately if the import does not use Exporter, the odds are low that there is any way to do that. And what I was promising was a way of getting the job done that would work with handrolled import methods.	[reply]