G'day All,

I've just read in "perlre: Other Modifiers": 

o  - pretend to optimize your code, but actually introduce bugs

[download]

It doesn't say anything further about these "bugs". There is a link to "s/PATTERN/REPLACEMENT/msixpodualngcer in perlop" which I thought might have some more information. Alas, no; all it says about /o is:

"If you want the pattern compiled only once the first time the variable is interpolated, use the /o option."

I did have a more extensive look around this area of perlop: no /o bug info found.

So, if anyone can tell me about these bugs, that would be appreciated.

I am aware that when a regex is compiled with /o, it is fixed; that is, the regex /$var/o won't change even if $var does. That's been the case since (at least) Perl3 — I wonder if that's the "bugs" to which the doco refers.

Not really part of the question, more background really, but my "/o bug" query came about as I was doing some benchmarking (born of idle curiosity). Code and results in the spoiler for those interested.

<Reveal this spoiler or all in this thread>

— Ken

In reply to Regex /o modifier: what bugs? by kcott

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