in reply to Capture not working

I don't think this has anything to do with captures.

The error message seems to report an unitialised value in the string concatenation, which means that <$file> is returning undef. So why is your die not working? Try changing the low precedence operator or to ||.

update: Yep, I'm wrong again.

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Re^2: Capture not working
by moritz (Cardinal) on Jan 08, 2009 at 13:51 UTC
    If you're unsure where the warning comes from, just run it through perl-5.10: 
    mlenz@wvbh074:~$ cat test.pl
use strict;
use warnings;
my $comment = '';
my $statement = '';
while ($statement !~ m{^(/\*.*\*/;)(.*)}s) { $statement .= <DATA> or d
+ie "Premature EOF\n"; }
print "Found type 1 comment: $1\n";

__DATA__
/* foo */;  stuff;
mlenz@wvbh074:~$ perl test.pl
Use of uninitialized value $1 in concatenation (.) or string at test.p
+l line 6, <DATA> line 1.
Found type 1 comment:

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    Here it tells you uninitialized value $1 explicitly.

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Re^2: Capture not working
by ikegami (Patriarch) on Jan 08, 2009 at 13:43 UTC

    I beg to differ ...uh agree with the OP 

    >perl -wle"while ('a'=~/(.)/, 0) {} print(qq{Found $1})"
Use of uninitialized value in concatenation (.) or string at -e line 1
+.
Found

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    Turns out $x .= <> doesn't even cause a warning at EOF?! 

    >perl -we"our $x; $x .= <>" <nul

>

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      Thank you, that's very helpful. I didn't know you can assign the results of a pattern operation to a list like this.

      I don't quite see in how far the EOF test was buggy though, since the data can neither contain blank lines nor lines containing nothing but a "0"...

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        I don't quite understand the last paragraph. Are you asking why the EOF test was buggy? No matter how many undef you add to $statement, it will never become false once it's true, so the die won't be executed.

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Re^2: Capture not working
by Corion (Patriarch) on Jan 08, 2009 at 13:39 UTC

    Indeed, the or die statement is not working, as it checks that $statement .= <$file> is not a false value, which it will be in most cases..

    Worng answer - see the answers of people actually testing their responses :)

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