Noted. Re-reading perldoc -f sort reveals that the sort of "magic" I thought I was seeing wasn't the case. $a and $b are package globals explicitly passed by Perl itself to the sort block (or subroutine of your definition). It's not a bare leftside-rightside comparison of whatever expressions you may provide. You have to explicitly use the $a and $b package global symbols, and $_ isn't $a/$b. Them's the rules.

I do indeed stand corrected.

Tommy
A mistake can be valuable or costly, depending on how faithfully you pursue correction

In reply to Re^5: Golf: reverse sort /etc/passwd by UID by Tommy
in thread Golf: reverse sort /etc/passwd by UID by Tommy

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.