[Python-ideas] re.compile_lazy - on first use compiled regexes

[Gregory P. Smith]

On Fri, Mar 22, 2013 at 3:31 PM, Ronny Pfannschmidt <
Ronny.Pfannschmidt at gmx.de> wrote:

> Hi,
>
> while reviewing urllib.parse i noticed a pretty ugly pattern
>
> many functions had an attached global and in their own code they would
> compile an regex on first use and assign it to that global
>
> its clear that compiling a regex is expensive, so having them be compiled
> later at first use would be of some benefit
>

It isn't expensive to do, it is expensive to do repeatedly for no reason.
 Thus the use of compiled regexes.  Code like this would be better off
refactored to reference a precompiled global rather than conditionally
check if it needs compiling every time it is called.

-gps


>
> but instead of all that reptetive code there should be an alternative to
> re.compile that waits with compilation for the first use
>
> -- Ronny
>
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