[Python-Dev] possible Tkinter speedup

[M.-A. Lemburg]

Fredrik Lundh wrote:
> 
> the _flatten method in Tkinter is one of the major performance
> bottlenecks for Python/Tk programmers.  the method "flattens"
> a nested sequence, by repeatedly adding tuples to each other.
> 
> obviously, this isn't very efficient if the sequences are longer
> than, say, five to ten items...  and has of course led to claims
> like "wxPython is a thousand times faster than Tkinter".
> 
> anyway, taking recent changes to Python into account, it should
> be possible to speed this up quite a bit.
> 
> the old code looked like this:
> 
>     def _flatten(tuple):
>         res = ()
>         for item in tuple:
>             if type(item) in (TupleType, ListType):
>                 res = res + _flatten(item)
>             elif item is not None:
>                 res = res + (item,)
>         return res
> 
> after a some trials and errors, here's my proposed replacement:
> 
>     def _flatten1(seq):
>         res = []
>         for item in seq:
>             if type(item) in (TupleType, ListType):
>                 res.extend(_flatten1(item))
>             elif item is not None:
>                 res.append(item)
>         return res
> 
>     def _flatten(seq):
>         return tuple(_flatten1(seq))
> 
> in my tests, this is slighly faster on very short sequences (two
> coordinate pairs, which is a common case for e.g. rectangles),
> and much faster on long sequences (polylines, polygons).
> 
> for example, for a 5000-point line, it's about 15 times faster.
> on a 10,000 point line, it's over 50 times faster.  etc.
> 
> comments?

Why not implement this in C and add it to _tkinter.c ?
It might even make a nice standard builtin...

-- 
Marc-Andre Lemburg
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