Declaring my variables in sort function?

kettle has asked for the wisdom of the Perl Monks concerning the following question:

I'm not quite clear on why the following code errs; why can't I declare another 'my' variable with the same name?

#!/usr/bin/perl -w

my ($a,$b,$c,@home);
@home = (1,2,2,23,10,9);
print map{$_."\n"} sort {my $a<=>my $b} @home;
[download]

This sort of problem does't always crop up so I'm really wondering why it does in this particular instance.

2006-04-13 Retitled by planetscape, as per Monastery guidelines
Original title: 'not quite clear'

Comment on Declaring my variables in sort function? Download Code

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Re: Declaring my variables in sort function? by Corion (Patriarch) on Apr 12, 2006 at 08:09 UTC
How "does it err" ? Have you looked at the documentation for the sort function ? The variables `$a` and `$b` are magical for the `sort` function and you should not declare them as lexical variables using `my`. In fact, you should not name any of your own variables `$a` or `$b`. As a general hint for receiving effective answers to your questions, see How (Not) To Ask A Question.	[reply] [d/l] [select]
Re: Declaring my variables in sort function? by strat (Canon) on Apr 12, 2006 at 08:10 UTC
sort uses the "global" variables $a and $b as comparing algrothm for the sort; you can't use other variables instead if you try to use my-variables instead, you are useing other variables and it won't work sort is the reason why $a and $b aren't checked by use strict; so IMHO it's a good idea to reserve these variables to sort `use strict; my @home = (1, 2, 23, 10, 9); print map { "$_\n" } sort { $a <=> $b } @home;` [download] Best regards, perl -e "s>>F>e=>y)\martinF)stronat)=>print,print v8.8.8.32.11.32"	[reply] [d/l]
Re: Declaring my variables in sort function? by perladdict (Chaplain) on Apr 12, 2006 at 10:47 UTC
Hi try like this `#!/usr/bin/perl -w my (@home); @home = (21,29,2,23,10,9); print map{$_. "\n"} sort { $a <=> $b} @home;` [download]	[reply] [d/l]