Chardet, file, ... and the Flexible String Representation

[Serhiy Storchaka]

09.09.13 22:27, random832 at fastmail.us написав(ла):
> On Mon, Sep 9, 2013, at 15:03, Ian Kelly wrote:
>> Do you mean that it breaks when overwriting Python string object buffers,
>> or when overwriting arbitrary C strings either received from C code or
>> created with create_unicode_buffer?
>>
>> If the former, I think that is to be expected since ctypes ultimately
>> can't
>> know what is the actual type of the pointer it was handed -- much as in
>> C,
>> that's up to the programmer to get right. I also think it's very bad
>> practice to be overwriting those anyway, since Python strings are
>> supposed
>> to be immutable.
>>
>> If the latter, that sounds like a bug in ctypes to me.
>
> I was talking about writing to the buffer object from python, i.e. with
> slice assignment.
>>>> s = 'Test \U00010000'
>>>> len(s)
> 6
>>>> buf = create_unicode_buffer(32)
>>>> buf[:6] = s
> TypeError: one character unicode string expected
>>>> buf[:7] = s
> ValueError: Can only assign sequence of same size
>>>> buf[:7] = 'Test \ud800\udc00'
>>>> buf[:7]
> 'Test \U00010000' # len = 6
>
> Assigning with .value works, however, which may be a viable workaround
> for most situations. The "one character unicode string expected" message
> is a bit cryptic.

Please report a bug on http://bugs.python.org/.