The thing is, for people with a clear understanding of what the parser is doing, using the side-effect of a command isn't that big of a deal. OTOH for people who are still picking up the language, not knowing the consequences of ignoring the return can realy freak you out.

I did something like the following once, thanks to cut-n-pasting someone else's solution. There was a lot of intervening code in the original case but it came down to this: 

#!/usr/bin/perl -w
my @list=(4,3,2,5,1);
 # db access here for more data.
 # the numbers that follow were real ugly in the original
 # code, like $sql->return->[0][2] and suchlike...
push @list, 45, 6, 24, 43, 9, # Comma not semicolon
map {$_ *= 2} @list;
print "@list\n";
# prints:
# 8 6 4 10 2 45 6 24 43 9 4 3 2 5 1

[download]

That was how I learned about abusing void context. =) Took me quite a while to spot that little goofup. If I'd written it the "right" way with a foreach: foreach (@list) { $_ *= 2; } I would have at least got a syntax error NEAR the error.

Of course, merlyn's fancy postfix for trick: $_++ for @l; in place of the map nets you an infinite loop in this case. =)

In any case, it seems wrong to ask perl to build up a return list from the map just to ignore it. If your only job is holding a nut while someone else tightens the bolt, you use a box-wrench, not a ratchet. Using a ratchet isn't "wrong" but it is still the wrong tool for the job. =)

Of course, now that I've gotten cocky, I abuse side effects ever so often myself. I just try not to do it to at work where some poor schmuck will have to puzzle out what I did.

--
$you = new YOU;
honk() if $you->love(perl)

In reply to Re: Re: setting values in anonymous hash by extremely
in thread setting values in anonymous hash by agoth

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.