The second method is better defensive programming. However, what it does is pretty much equivalent to the following: 
BEGIN {
    sub FILENAME() { '/path/to/file/to/munge' }
}

[download]
Because FILENAME is actually a subroutine, it cannot be interpolated in quotes. In other words, the following are not synonymous: 
my $filename = "/path/to/file/to/munge";
print "$filename";

use constant FILENAME => '/path/to/file/to/munge'; 
print "FILENAME";

[download]
The first example prints the filename, the second just prints "FILENAME".

That's a minor issue, but it does crop up from time to time (particularly when I'm writing an open X, Y or die statement).

Cheers,
Ovid

Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.

In reply to (Ovid constants) Re: my $var; vs. use constant VAR = ''; by Ovid
in thread my $var = ''; vs. use constant VAR => ''; by antihero

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.