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[Python-Dev] [docs] undocumented argtypes magic in ctypes?

Eli Bendersky eliben at gmail.com
Thu Mar 7 15:09:58 CET 2013 
On Thu, Mar 7, 2013 at 5:53 AM, Thomas Heller <theller at ctypes.org> wrote:

>         ctypes seems to auto-convert arguments when argtypes is
>>         specified. This
>>         fact is documented. However, I'm not sure whether this
>>         auto-conversion
>>         is advanced enough to apply byref. Because otherwise, DIRENT is
>>         certainly not convertible to DIRENT_p
>>
>>     If argtypes specify a 'POINTER(X)' type as an argument, then ctypes
>>     automatically applies byref() if an 'X' instance is passed to the
>>     actual call.  This is by design, but I'm not sure if it is documented
>>     or not.
>>
>>     However, if argtypes is not given, this does (and of course cannot)
>>     work.
>>
>> Great, thanks for confirming this, Thomas. I had the feeling it's a
>> documentation issue (hence I sent it to the docs@ list first), because
>> the behavior seems very deliberate and looking at the code of ctypes I
>> did see conversions going on.
>>
>> Have I missed that this is documented somewhere, or should I open a docs
>> issue?
>>
>
> I didn't find anything in the docs (in the two minutes I spent for that),
> so please open a docs issue, or, better, fix it.


http://bugs.python.org/issue17378, has a patch already. Please take a look.

Eli
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