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 I think that "use vars" is obsolete and that "our" is prefered.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

In reply to standard perl module and BEGIN block. by hartzell

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.