This gotcha is explained in the standard documentation for the conditional operator in perlop: 
       Because this operator produces an assignable result, using
       assignments without parentheses will get you in trouble.
       For example, this:
 
           $a % 2 ? $a += 10 : $a += 2
 
       Really means this:
 
           (($a % 2) ? ($a += 10) : $a) += 2
 
       Rather than this:
 
           ($a % 2) ? ($a += 10) : ($a += 2)

[download]

In reply to Re: Why won't $' work in a trinary operation? by chipmunk
in thread Why won't $' work in a trinary operation? by satchboost

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.