[pypy-dev] [pypy-commit] pypy default: Optimize match.group('name') by making it a module dict.

[Carl Friedrich Bolz]

On 01/11/2013 04:57 PM, Alex Gaynor wrote:
> Hi Carl,
>
> The reason is that the dict has similar properties to a module dict:
>
> 1) keys are written only once
> 2) lookups are almost always by constant strings
>
> In typical usage a the groupindex dict is never mutated after its
> initial creation, and reads from it are by a precise name of a field,
> therefore by having it be a moduledict we can make re.group('name') be free.
>
> I'll go ahead and add a comment with this info.
>

does that mean that the dict (which is created during parsing) is
stored on the regex object? If yes, that is the connection that I
didn't understand.

CF


> Alex
>
> On Fri, Jan 11, 2013 at 2:17 AM, Carl Friedrich Bolz <cfbolz at gmx.de
> <mailto:cfbolz at gmx.de>> wrote:
>
>     Hi Alex,
>
>     I don't really understand the first change of this commit. Why is it a
>     good idea to change the groupdict of the re parser to be a module dict?
>     There are supposed to be "not too many" module dicts, because they are
>     promoted on read. So I don't get why this is a sensible change.
>
>     Would you please add a comment to the point where the module dict is
>     instantiated why this is a good idea, and ideally also a test_pypy_c
>     test.
>
>     Cheers,
>
>     Carl Friedrich
>
>
>
>
>
>
> --
> "I disapprove of what you say, but I will defend to the death your right
> to say it." -- Evelyn Beatrice Hall (summarizing Voltaire)
> "The people's good is the highest law." -- Cicero