Of course you can always use require for Data::Dumper module, i.e. as in 

BEGIN {
   use constant DEBUG => 1;
   if (DEBUG) {
      require Data::Dumper;
   }
}

[download]
However, this would not work for warnings since it works during compilation time. Moreover, as a rule of thumb I would recommend to always include both use strict and use warnings in every perl program. Believe it or not, it will catch a lot of errors and typos and reduce the debugging time greatly. Even for the advance programming you can always localize the effect by temporarily switching off both warnings and strict with no warnings and no strict directives.

In reply to Re: syntax question: conditional 'use' statement? by caelifer
in thread syntax question: conditional 'use' statement? by Anonymous Monk

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.