Regex from a string

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

What Im trying to do is allow a user to specify a regex through form submission, then have the regex run on a piece of data.

In terms of processing the regex I've tried the following with now luck

my $str = "Hello my name is Kevin";
my $regex = $form->query(...);
#Value of regex : "/Hello\smy\name\sis\s(\w.*)/"

$str =~ $regex;
[download]

I've also tried the string statement as the following

$str =~ /$regex/; #where omitting / in $regex
eval($str =~ /$regex/);
eval($str =~ $regex);
[download]

Not one of the above returns a value for $1 Any ideas, the regex works fine on its own when used in a traditional method

Comment on Regex from a string Select or Download Code

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Re: Regex from a string by dragonchild (Archbishop) on Jun 17, 2005 at 14:56 UTC
You're looking for qr//. Note: what you're trying to can be a really bad thing. The reason is because regexes can theoretically execute arbitrary Perl code using the (?{...}) construct. Now, `use re 'eval';` has to be in effect, but if that gets put in by a maintenance programmer later, you're in trouble. Update: Link to apparently pirated material removed. My criteria for good software: Does it work? Can someone else come in, make a change, and be reasonably certain no bugs were introduced?	[reply] [d/l]
Re^2: Regex from a string by ghenry (Vicar) on Jun 17, 2005 at 14:57 UTC
Shame on you dragonchild for linking to pirate O'Reilly books. Walking the road to enlightenment... I found a penguin and a camel on the way..... Fancy a yourname@perl.me.uk? Just ask!!!	[reply]
Re^3: Regex from a string by davidrw (Prior) on Jun 17, 2005 at 15:10 UTC
Ug. That's the exact same site that got me recently, too.. A quick google search on this topic found it very high in the results here, too..	[reply]
Re^4: Regex from a string by ghenry (Vicar) on Jun 17, 2005 at 15:17 UTC
Re: Regex from a string by TedPride (Priest) on Jun 17, 2005 at 15:38 UTC
Well, this works fine: `$_ = 'Hello my name is A0'; my $r = 'Hello\smy\sname\sis\s(\w.*)'; print $1 if m/$r/;` [download] But I can't figure out how to let the user set flags like i. Eval is generally a bad idea unless you know exactly who is going to be using your script.	[reply] [d/l]