Neil Schemenauer <n...@arctrix.com> wrote:
> We should use duck-typing and that means a special method, I
> think. We could introduce a new one but __bytes__ looks like it
> can work. Otherwise, maybe __ascii__ is a good name.
I poked around the Python 3 source. Using __bytes__ has some
downsides, e.g. the following would happen:
>>> bytes(12)
b'12'
Perhaps that's a little too ASCII-centric. OTOH, UTF-8 seems to be
winning the encoding war and so the above could be argued as
reasonable behavior. I think forcing people to explicitly choose an
encoding for str objects will be sufficient to avoid the bytes/str
mess we have in Python 2.
Unfortunately, that change conflicts with the current behavior:
>>> bytes(12)
b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'
Would it be too disruptive to change that? It doesn't appear to be
too useful and we could do it using a keyword argument, e.g.:
bytes(size=12)
I notice something else surprising to me:
>>> class Test(object):
... def __bytes__(self):
... return b'test'
...
>>> with open('test', 'wb') as fp:
... fp.write(Test())
...
Traceback (most recent call last):
File "<stdin>", line 2, in <module>
TypeError: 'Test' does not support the buffer interface
I'd expect that to write b'test' to the file, not raise an error.
Regards,
Neil
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