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Re: psss...I want to move from Perl to Python

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  Re: psss...I want to move from Perl to Python MRAB <python@mrabarnett.plus.com> - 2016-01-31 03:43 +0000

#102329 — Re: psss...I want to move from Perl to Python

On 2016-01-31 01:56:51, "Steven D'Aprano" 
<steve+comp.lang.python@pearwood.info> wrote:

>On Sunday 31 January 2016 09:18, Gregory Ewing wrote:
>
>>  Rustom Mody wrote:
>>>  1. One can use string-re's instead of compiled re's
>>
>>  And I gather that string REs are compiled on first use and
>>  cached, so you don't lose much by using them most of the
>>  time.
>
>Correct. The re module keeps a cache of the last N regexes used, for 
>some
>value of N (possibly 10?) so for casual use there's no real point to 
>pre-
>compiling other than fussiness.
>
In Python 3.5, it's 512.
>
>But if you have an application that makes heavy-duty use of regexes, 
>e.g.
>some sort of parser with dozens of distinct regexes, you might not want 
>to
>rely on the cache.
>
It's slightly faster to use a pre-compiled regex because it won't have 
to look it up in the cache, although most of the time it probably won't 
matter.

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