I've been setting up a standard module.pm template for several folks to use. The perlmod man page suggests this:

BEGIN {
    use Exporter   ();
    our ($VERSION, @ISA, @EXPORT, @EXPORT_OK, %EXPORT_TAGS);

    # set the version for version checking
    $VERSION     = 1.00;
    # if using RCS/CVS, this may be preferred
    $VERSION = sprintf "%d.%03d", q$Revision: 1.1 $ =~ /(\d+)/g;

    @ISA         = qw(Exporter);
    @EXPORT      = qw(&func1 &func2 &func4);
    %EXPORT_TAGS = ( );     # eg: TAG => [ qw!name1 name2! ],

    # your exported package globals go here,
    # as well as any optionally exported functions
    @EXPORT_OK   = qw($Var1 %Hashit &func3);
}
[download]

But that ExtUtils-ModuleMaker-0.32 (which I found via a module best-practices thread) does this:

BEGIN {
        use Exporter ();
        use vars qw ($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
        $VERSION     = 0.01;
        @ISA         = qw (Exporter);
        #Give a hoot don't pollute, do not export more than needed by 
+default
        @EXPORT      = qw ();
        @EXPORT_OK   = qw ();
        %EXPORT_TAGS = ();
}
[download]

and other examples (that I can't find at the moment) do without the BEGIN block. I'd like to be able to explain the differences to other folks, but don't know all of the history, so I have a few questions:

1. I think that "use vars" is obsolete and that "our" is prefered. But I think that using "our" impacts backward compatibility? Or is there more going on?
2. I think that modules should put their module setup stuff (VERSION, ISA, EXPORT*) in a BEGIN block so that it's available at compile time (since that what the BEGIN block does...), but I'm not clear on who takes advantage of it.
3. In order to leverage the justification in 2., should I put all of the module's that the package in question "uses" into the begin block, or just the module def'n stuff?

g.

Edit by tye, replace PRE with CODE

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