It is better to avoid using special variables '$a' and '$b'.
Use different name, e.g. '$_a', or longer meaningful name, or uppercase letter.
#!/usr/bin/perl -lw

use strict;

my ($a, $b) = (7, 5);
($b, $a) = ($a, $b);

print join ' ', sort { $a <=> $b } qw( 5 28 1 );

print "$b $a";

[download]
STDOUT: 
5 1 28
7 5

[download]
STDERR: 
"my $a" used in sort comparison at prog.pl line 8.
"my $b" used in sort comparison at prog.pl line 8.

[download]
I suggest to update examples with using of different names ;)

In reply to Re: Python tricks by rsFalse
in thread Python tricks by pme

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.