Consider a novice-perl maintainer. He has to modify an old module. He uses the vars $a and $b to effect some change. Unknown to him however some part of the code calls a subroutine that overwrites $a and $b. He gets weird results and cant explain them. He looks in perlvar but sees no mention. He doesnt even know that sort is being used so he doesnt know to look in perlfunc. He doesnt look at the strict documentation because like a good novice he has strict turned on already. How other by asking or by luck is he to know or figure out what the hell is going on? (Oh im assuming that as a novice he found using the debugger as imposing as I did at the start and doesnt use it, or doesnt know how at all.)

See what I mean?

But you're right that instead of submitting a bug report, I should submit a patch. Which I will do.

Yves / DeMerphq
--
When to use Prototypes?
Advanced Sorting - GRT - Guttman Rosler Transform

My answer was tongue firmly in cheek. Note the tone and the :)'s scattered about. But please, submit a patch.

To clear up a misconception though, your "action at a distance" horror scenario there won't happen. No sir. $a and $b are (apparently) local'd to the block:

@list=qw( one two three four five );

$a="Hello";
$b="World";
sort { $a <=> $b } @list;
print "$a $b";  # Hello World
[download]

I knew this. Several others in channel this morning knew this. But in an ironic twist of events, I can't find where that localization is documented. I think I see it in the Perl source...but not in the docs.

Ah, but the "action at a distance" most certainly does occur. If you create a sorting sub in one module and use it in another ... Look at the following code:

my $a = 5;

my @b = reverse (0 .. 9);
print "@b\n";

sub boo {
$a <=> $b
}

@b = sort boo @b;
print "@b\n";
print $a,$/;
----
9 8 7 6 5 4 3 2 1 0
0 1 2 3 4 9 8 5 6 7
5
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Note the lack of sorting after 4. :-)

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