I've generally found that Perl's functions that operate on strings (join, index, etc.) are typically very fast. You can compare with other solutions using Benchmark; you can profile to find hotspots (e.g. Devel::NYTProf).

I can see a number of micro-optimisations you could make: replace $ref_len - 1 with $#$ref and replace 1 + $#$ref with $ref_len. That may gain you absolutely nothing but, I suppose, the code would be a little neater.

You could do a single join. Then repeatedly chop the front off (index to locate JOIN then substr); again, that may gain you nothing but perhaps worth a try.

I, and no doubt others, would be interested in the results if you do decide to benchmark this against your current "brute force solution", a regex solution, and anything else you may have come up with.

— Ken

In reply to Re^3: CPAN Module to determing overlap of 2 lists? by kcott
in thread CPAN Module to determing overlap of 2 lists? by wazat

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.