Re^2: Comparing two variables when one variable includes a regexp...

Surely all these replies that fix one example out of an infinite number of possible user inputs are missing the point?

If I understood the original post, $NetPattern is to be read from the command line, so the example, mistaken bracketing and all, was just an example. The question was

If a user enters a command-line regular expression that gets pushed into a variable, what is the most reliable way to use that variable to compare it against another variable that is a string?

In our answers, we should be explaining how to validate a user-supplied string before interpolating it into a regex. A simple error like [ without matching ] is the least of our worries.

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Re^3: Comparing two variables when one variable includes a regexp... by jettero (Monsignor) on May 01, 2008 at 19:24 UTC
That's an excellent point actually. I'll amend my answer, although I covered it somewhat. Assuming you actually trust the user, this seems like a sane way to do it. `my $regexp = <$file_handle>; my $creg = eval { qr($regexp) }; if( $@ ) { warn "regex error: $@"; } else { if( $something =~ $creg ) { # do wonderful things. } }` [download] I apparently skipped the meat of the question because it seemed clear to me that the reason the matching failed was because of an interpolation problem with a test regexp that he generated between quotes and he wasn't actually reading it from the user -- which would have likely worked the way he had it. -Paul	[reply] [d/l]

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Re^3: Comparing two variables when one variable includes a regexp...
by jettero (Monsignor) on May 01, 2008 at 19:24 UTC

my $regexp = <$file_handle>;
my $creg   = eval { qr($regexp) };

if( $@ ) {
   warn "regex error: $@";

} else {
   if( $something =~ $creg ) {
      # do wonderful things.
   }
}
[download]

I apparently skipped the meat of the question because it seemed clear to me that the reason the matching failed was because of an interpolation problem with a test regexp that he generated between quotes and he wasn't actually reading it from the user -- which would have likely worked the way he had it.

-Paul

[reply]
[d/l]