Don't lexicalize them with my $a or my $b if you want to be able to us
+e them in the sort() comparison block or function.

[download]
But, on the other hand you can localize them when needed: 
$ perl -we '
   local $a = 1;
   @h = sort {$a <=> $b} keys %hash;
   print "@h\n";> %hash = map { $_ , undef } 0 .. 3;
   @h = sort {$a <=> $b} keys %hash;
   print "@h\n";
'
0 1 2 3

[download]

In reply to Re^2: question about: my $a AND sort {$a <=> $b} keys %hash by Laurent_R
in thread question about: my $a AND sort {$a <=> $b} keys %hash by rsFalse

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