Re: Common Perl Pitfalls

Of course if you had meant the string $to_replace is an actual regex to match against, you're better off using the qr operator:

I don't get this point. You started off that section with:

$to_replace='some_string';
$my_string=~ s/$to_replace/$better_data/;
[download]

and doomed this catastrophically unsafe, because $to_replace may actually contain characters that have a special meaning.

But if $to_replace is actually a regexp, the premises is gone -- any special characters are intentional. In fact, it's quite fine in that case to use the above.

Comment on Re: Common Perl Pitfalls Download Code

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Re^2: Common Perl Pitfalls by Joe_ (Beadle) on Apr 10, 2012 at 18:21 UTC
I actually meant to say that one shouldn't use a scalar as a regex anyway. I meant to say that, even if your correct semantics didn't require the use of \Q and \E (i.e. you actually needed the metacharacters) then you're better off using the qr// operator instead of building your regex as a literal string.	[reply]
Re^3: Common Perl Pitfalls by JavaFan (Canon) on Apr 10, 2012 at 21:29 UTC
Well, that's nice you want to say that, but can you back up your statement with an argument?	[reply]
Re^4: Common Perl Pitfalls by Joe_ (Beadle) on Apr 10, 2012 at 22:10 UTC
Several, actually. For starters, I happen to believe it's better for readability. Another thing is, the regex modifiers "come with it". So you can include things like the 'x' modifier right along with the regex; if you're using a string as a regex, on the other hand, you have to remember which modifiers you need when you finally decide to use it in a match. Also, even though it doesn't show in this example, qr// is more efficient as (IIRC) it pre-compiles its regex before matching: i.e. you can build the regex once and use it several times. I use the qr// operator this way to make my regexes "modular". Anyway, you already know that I've been wrong about efficiency before :), so please correct me if you have a different say on the matter. I'm here to learn...	[reply]
Re^5: Common Perl Pitfalls by JavaFan (Canon) on Apr 10, 2012 at 23:19 UTC
Re^6: Common Perl Pitfalls by Joe_ (Beadle) on Apr 10, 2012 at 23:43 UTC
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Re^6: Common Perl Pitfalls by Jenda (Abbot) on Apr 11, 2012 at 16:23 UTC
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