Sorry I disagree that this is a good example - "by the book" - of a closure, because it's far to magic.

Each closure has a new instance of $i which is mutable, looking at the code I would expect either always the same instance of $i or $i being an alias of an immutable literal... but it's neither of these...

for my $i (1..3) { 
  $numbers{$i} = sub { $i++;print $i }; 
}

[download]

Cheers Rolf

UPDATE:

OK my problem derived from the difference between range operator and comma operator in producing lists:

  DB<37> for my $i (1,2,3) { $numbers{$i} = sub { $i++;print $i }; pri
+nt \$i}
SCALAR(0x9338210)SCALAR(0x92bdc90)SCALAR(0x9338190)
  DB<38> &{$numbers{1}}
Modification of a read-only value attempted at (eval 43)[/usr/share/pe
+rl/5.10/perl5db.pl:638] line 2.

[download]

In reply to Re^2: Constant value in anonymous sub (closures & aliases) by LanX
in thread Constant value in anonymous sub by Sewi

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