You said:

sub _is_start_pattern {
 my ($class, $line) = @_;
 return ($line =~ $class->START_PATTERN);
 # I really wish we could do
 #return ($line =~ $class::START_PATTERN);
}

[download]

Well, if you really want to you can always do something like this:

{
    package PB_File;
    
    our $START_PATTERN = "base-pattern";
    
    sub pattern {
        my $class = shift;
        {
            no strict 'refs';
            ${"${class}::START_PATTERN"};
        };
    }
}

{
    package An_AR;
    use base qw(PB_File);
    
    our $START_PATTERN = "sub-pattern";
};

use Test::More tests => 2;
is( PB_File->pattern, 'base-pattern' );
is( An_AR->pattern, 'sub-pattern' );

[download]

However, for me, you're not repeating any more information by having a method call. Compare:

our $START_PATTERN = qr(^(\d)\s+\1$);
sub START_PATTERN { qr(^(\d)\s+\1$) };

[download]

Okay - you have to type one more character :-)

You also have the advantage that, if you use methods, any future code maintainer doesn't have to learn (or remember) that some package globals are "special".

In reply to Re^5: class constants in derived classes by adrianh
in thread class constants in derived classes by leriksen

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.