Re^2: Using eval to s/// with a pattern supplied on the command-line

Yes, but this code

for (qw(your hand is too cold to hold)) 
{
    s/cold/new/;
    print $_, "\n";
}
[download]

should run and DWIM. I have no idea why it doesn't. I get Modification of a read-only value attempted at C:\t.pl line 3.

holli, /regexed monk/

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Re^3: Using eval to s/// with a pattern supplied on the command-line by betterworld (Curate) on Mar 16, 2005 at 22:08 UTC
This is because the qw-list is a literal, thus not modifyable.	[reply]
Re^3: Using eval to s/// with a pattern supplied on the command-line by Limbic~Region (Chancellor) on Mar 16, 2005 at 23:28 UTC
holli, Would you expect `"cold" =~ s/cold/new/;` to work? Remember that the looping variable in a Perl style for loop is an alias to that which is being looped over. Cheers - L~R	[reply] [d/l]
Re^4: Using eval to s/// with a pattern supplied on the command-line by holli (Abbot) on Mar 17, 2005 at 05:52 UTC
No, I don't. But the regex operates on `$_` and therefore I would have expected to be changeable. holli, /regexed monk/	[reply] [d/l]
Re^5: Using eval to s/// with a pattern supplied on the command-line by Limbic~Region (Chancellor) on Mar 17, 2005 at 13:13 UTC
holli, But as I said, $_ isn't a copy it is an alias. If you were to do the following: `my @word = qw(one two three four five); for ( @word ) { $_ = uc( $_ ); } print "$_\n" for @word;` [download] You find the underlying array being modified. If the thing being looped over can't be modified you can't change the looping variable. You need to make an explicit copy if you want to do that. Cheers - L~R	[reply] [d/l]