[Python-Dev] Replacement for array.array('u')? (original) (raw)

Victor Stinner vstinner at redhat.com
Fri Mar 22 03:45:03 EDT 2019

Hi,

Internally, CPython has a _PyUnicodeWriter which is an efficient way to create a string but appending substrings or characters. _PyUnicodeWriter changes the internal storage format depending on characters code points (ascii or latin1: 1 byte/character, BMP: 2 b/c, full UCS: 4 b/c). I tried once to expose it in Python, but I wasn't convinced by performances. The overhead of method calls was quite significant, and I wasn't convinced by "writer += str" performance neither. Maybe I should try again. PyPy also has such object. It avoids the "str += str" hack in ceval.c to avoid very poor performance (_PyUnicodeWriter also uses overallocation which can be controlled with multiple parameters to reduce the number of realloc).

Another alternative would be have to add a "strarray" type similar to bytes/bytearray couple.

Is is what you are looking for? Or do you really need array.array API?

Victor

Le ven. 22 mars 2019 à 08:38, Greg Ewing <greg.ewing at canterbury.ac.nz> a écrit :

A poster on comp.lang.python is asking about array.array('u'). He wants an efficient mutable collection of unicode characters that can be initialised from a string. According to the docs, the 'u' code is deprecated and will be removed in 4.0, but no alternative is suggested. Why is this being deprecated, instead of keeping it and making it always 32 bits? It seems like useful functionality that can't be easily obtained another way. -- Greg

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