substitution not recompile

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

I have the following code

$foo = "some sentence x";
$val = 1;

while ($val < 5) {
  $foo =~ s/x/$val/;
  print "$val $foo\n";
  $val++;
}
[download]

I was expecting the substitution to be recompile everytime and new val is used. But not in thise case... why?
Thanks!

Comment on substitution not recompile Download Code

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Re: substitution not recompile by ikegami (Patriarch) on Mar 24, 2005 at 15:11 UTC
It doesn't work because you removed the 'x' the first time around. `$val = 1; while ($val < 5) { $foo = "some sentence x"; # Move this here $foo =~ s/x/$val/; print "$val $foo\n"; $val++; }` [download] or `$foo = "some sentence x"; $val = 1; while ($val < 5) { my $foo = $foo; # Add this. $foo =~ s/x/$val/; print "$val $foo\n"; $val++; }` [download]	[reply] [d/l] [select]
Re: substitution not recompile by polettix (Vicar) on Mar 24, 2005 at 15:14 UTC
The first time the substitution is executed you lose your x in `$foo`; next times, there's no x to substitute. You're probably looking for: `$template = "some sentence x"; $val = 1; while ($val < 5) { $foo = $template; $foo =~ s/x/$val/; print "$val $foo\n"; $val++; }` [download] Flavio -- Don't fool yourself.	[reply] [d/l] [select]
Re^2: substitution not recompile by manav (Scribe) on Mar 24, 2005 at 15:30 UTC
Or maybe `$template = "some sentence x"; for $val (1..4) { ($foo = $template) =~ s/x/$val/; print "$val $foo\n"; }` [download] Manav	[reply] [d/l]