in reply to Substituting without modifying

If I understand your question... You want to perform a substitution on the value in $foo, without changing the value of $foo or copying the value to another variable first?

I think that you will be able to meet any two of those three requirements. :)

Here's something to consider, although it requires $foo to be a package variable rather than a lexical, and still involves copying the value: 

$foo = "bar baz";
{
  (local $foo = $foo) =~ s/bar/quux/;
  # do something with the modified $foo
}
# now the original $foo is back again

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BTW, there is nothing wrong with your use of my inside the parentheses.

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Re: Re: Substituting without modifying
by sierrathedog04 (Hermit) on May 20, 2001 at 22:51 UTC
    Your method works great using lexical variables as well, because the perl interpreter correctly interpolates the temporary value of $foo when that temporary value is in scope. 
    use strict;
my $foo = "bar baz";
{
  (my $foo = $foo) =~ s/bar/quux/;
  # do something with the modified $foo
    $foo = "changed it";
    print "The temporary value of foo is $foo.\n";
}
# now the original $foo is back again
print "The original value of foo is $foo.\n";

    [download]
    Running under ActiveState 5.6.1 and Windows ME, the above code first returns the temporary value of "changed it" and then the original value of "bar baz".
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