I've come to similar solutions as footpad with slight variations.

In the first case a required module isn't installed and the script dies with a link to the dist on CPAN: 

eval("use XML::Simple 'XMLin'"); # required xml parser
if($@){&install_xml_simple(); exit}

sub install_xml_simple
{
print header; print qq~Install 
<a href='http://search.cpan.org/search?dist=XML-Simple'>XML::Simple</a
+>~; 
}

[download]
Second case just causes some form buttons and text to not be printed later: 
my$trade = 0;
eval("use Compress::Zlib"); 
unless($@){$trade = 1} # if installed enable export/import

[download]
And another switch if the script doesn't find a self-created data file: 
use vars qw($xpdat1 $dat1); 
my($xpdata,$data,$md,$nodat) = 0; # vars for next block
my$df = 'some.data';

if(-e $df){ 
     if(eval "require '$df'"){
          $md = (stat($df))[9];
          $xpdata = $xpdat1;
          $data = $dat1;
          }
     }
else{ $nodat = 1 }

[download]

In reply to Re: Re: runtime "use" statements via string eval by epoptai
in thread runtime "use" statements via string eval by geektron

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.