[Python-Dev] RFC: Add a new builtin strarray type to Python? (original) (raw)

Victor Stinner victor.stinner at haypocalc.com
Mon Oct 3 04:19:53 CEST 2011

Le dimanche 2 octobre 2011 15:25:21, Antoine Pitrou a écrit :

I don't know why you're saying that. The concatenation optimization worked in 2.x where the "str" type also used only one memory block. You just have to check that the refcount is about to drop to zero. Of course, resizing only works if the two unicode objects are of the same "kind".

Oh, I see. In Python 2.7, bytes+=bytes calls PyMem_Realloc() on then writes the new characters to the result. It doesn't overallocate as bytearray (which overallocate +12,5%).

I restored this hack in Python 3.3 using PyUnicode_Append() in ceval.c and by optimizing PyUnicode_Append() (try to append in-place). str+=str is closer again to ''.join:

str += str: 696 ms ''.join(): 547 ms

I disabled temporary the optimization for wstr string in PyUnicode_Resize() because of a bug. I disabled completly resize on Windows because of another bug.

Victor

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