Exporter::Heavy Ordering Shenanigans?

tadman has asked for the wisdom of the Perl Monks concerning the following question:

It doesn't seem to be specified in the documentation, but apparently there are ordering issues with Exporter:

use Foo qw[ baz :bar ];  # ERROR: ":bar" not exported
use Foo qw[ :bar baz ];  # OK
[download]

Did I miss the part where they talk about having to put your sets first? Either way, this seems to be an oversight in Exporter::Heavy.

What about this patch?

*** Heavy.pm    Wed May 15 19:38:18 2002
--- /usr/local/lib/perl5/5.6.1/Exporter/Heavy.pm    Wed May 15 19:35:5
+1 2002***************
*** 36,48 ****
          }
      }
  
!     if ($imports[0] =~ m#^[/!:]#){
          my $tagsref = \%{"${pkg}::EXPORT_TAGS"};
          my $tagdata;
          my %imports;
          my($remove, $spec, @names, @allexports);
          # negated first item implies starting with default set:
!         unshift @imports, ':DEFAULT' if $imports[0] =~ m/^!/;
          foreach $spec (@imports){
          $remove = $spec =~ s/^!//;
  
--- 54,66 ----
          }
      }
  
!     if (grep {m#^[/!:]#} @imports){
          my $tagsref = \%{"${pkg}::EXPORT_TAGS"};
          my $tagdata;
          my %imports;
          my($remove, $spec, @names, @allexports);
          # negated first item implies starting with default set:
!         unshift @imports, ':DEFAULT' if (grep{m/^!/} @imports);
          foreach $spec (@imports){
          $remove = $spec =~ s/^!//;
[download]

Is this making it worse, or is this already patched in the more recent versions?

Comment on Exporter::Heavy Ordering Shenanigans? Select or Download Code

Replies are listed 'Best First'.
Re: Exporter::Heavy Ordering Shenanigans? by IlyaM (Parson) on May 16, 2002 at 05:46 UTC
From perldoc Exporter: `If the first entry in an import list begins with !, : or / then the list is treated as a series of specifications which either add to or delete from the list of names to import. They are processed left to right.` [download] So it is documented but probably not very clearly. On the other hand I fail to see why it should be this way. IMHO it is not Perlish (i.e. it is no DWIM). I've been biten by it myself. Once I spent about an hour trying to understand what the hell is going on and why I can't get Exporter work when I placed `:foobar` at the end of the import list. -- Ilya Martynov (http://martynov.org/)	[reply] [d/l] [select]
Re: Exporter::Heavy Ordering Shenanigans? by chromatic (Archbishop) on May 16, 2002 at 03:55 UTC
It's not patched in the recent versions, and I don't know if that's the right fix. If I did, I'd probably drop the second change. The comment seems fairly important.	[reply]
Re: Re: Exporter::Heavy Ordering Shenanigans? by tadman (Prior) on May 16, 2002 at 05:03 UTC
I don't expect that this would be encountered frequently, but you would get unusual behaviour if you did something like: `use Foo qw[ :bar !:frank ];` The boolean logic here is kind of fuzzy, so YMMV. The second change was one of those "It Seemed Like A Good Idea At The Time" things, so you're probably right.	[reply] [d/l]