[issue21057] TextIOWrapper does not support reading bytearrays or memoryviews

[STINNER Victor]

STINNER Victor added the comment:

> class MyByteStream(BytesIO):
>    def read1(self, len_):
>        return memoryview(super().read(len_))
> bs = MyByteStream(b'some data in ascii\n')

I guess that you are trying to implement a zero-copy I/O. The problem is that BytesIO does copy data. Example:

>>> data=b'abcdef'
>>> x=io.BytesIO(data)
>>> x.read() is  data
False

Before trying to avoid copies in the "buffered" layer, something should be done for the "raw" layer (BytesIO in this case).

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue21057>
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