Re: [ctypes-users] wrapping api calls with decorators

[Thomas H. <th...@py...>]

Niki Spahiev <ni...@vi...> writes:

> Thomas Heller wrote:
>> Then, it inspects the original function.  If there's no function body
>> (empty function bodies always have a 4-byte byte code), it creates a
>> code string containing a function body which simply contains
>>   'return _api_(<functions arguments>)'.
>> Then, the byte code of the function is patched: LOAD_GLOBAL <_api_>
>> opcodes are replaced by 'LOAD_CONST <exported_function>' opcodes.
>> This uses a variant of Raymond Hettinger's cookbook recipe
>> http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/277940
>> This approach is somewhat hacky, but I were not able to find a better
>> approach.  If there are better ideas, please let me know.
>
> Why not use nested scopes for _api_ resolution?

Because there is no nested scope.

Anyway, having posted the above and having thought over it the weekend,
I should probably drop the magic at all, and assign the native callable
to a function attribute. So the example becomes:


@ stdcall(DWORD, "kernel32", [HMODULE, POINTER(c_char), c_ulong])
def GetModuleFileNameA(handle=0): # 0 means current module
    buf = create_string_buffer(256)
    if 0 == GetModuleFileNameA._api_(handle, buf, sizeof(buf)):
        raise WinError()
    return buf.value

Thomas