I'll admit I just skimmed a bit, but can't find what you're talking about. Are you talking about shmem's solution for your line 19 similar to: 
$foo = ( split /pattern/, $string ) [ number ];

[download]
??? If that's the case, then look very carefully and you'll realize that the bracketed portion is not the optional third parameter to split(). The construct: 
( returns_a_list )[ index ]

[download]
or 
( returns_a_list )[ index, index ]

[download]
is called an array slice (or list slice). The indexes are the only ones from the list/array that end up being returned. The parentheses are there basically to bind the index to the whole list that's being returned.

List slices are a very handy idiom, and can be used to great effect in Perl.

Like lots of conveniences in Perl or any other higher-level dynamic language, this can also be abused since there are sometimes much more efficient solutions. Learning when to use slices and when to avoid generating the whole list to use just part of it is a classic machine time/programmer time trade-off. I always try to err on the side of saving programmer time until I actually need to worry about a specific hotspot in a program.


Christopher E. Stith

In reply to Re^3: printing array reference and storing this data in a hash. by mr_mischief
in thread printing array reference and storing this data in a hash. by mikejones

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.