[pypy-dev] How to get the return value from pypy function for C code

[Amaury Forgeot d'Arc]

2015-05-13 9:55 GMT+02:00 Yicong Huang <hengha.mao at gmail.com>:

> Thanks for your advices!
> But your code seems to only solve the problem about how to pass the
> function parameter from C to Python.
> In the document example:
>
> char source[] = "from cffi import FFI\n\ffi = FFI()\n\@ffi.callback('int(int)')\n\def func(a):\n\    print 'Got from C %d' % a\n\    return a * 2\n\ffi.cdef('int callback(int (*func)(int));')\n\c_func = ffi.cast('int(*)(int(*)(int))', c_argument)\n\c_func(func)\n\print 'finished the Python part'\n\";
> int callback(int (*func)(int)){
>     printf("Calling to Python, result: %d\n", func(3));}
>
> We are able to pass the function paramter '3' to python function func(a).
> But how could we extract the function result '6' to C code?
> In CPython, there is  'PyObject_CallObject', which returns python
> fucntion result.
> Does pypy have similar API?
>

But don't you have it already? the func(3) above should return the integer
6!



>
> On Wed, May 13, 2015 at 3:25 PM, Amaury Forgeot d'Arc <amauryfa at gmail.com>
> wrote:
>
>> Hi,
>>
>> 2015-05-13 7:39 GMT+02:00 Yicong Huang <hengha.mao at gmail.com>:
>>
>>> From the document " "Embedding Pypy", we got the method to call python
>>> function from C code.
>>> But there are no examples on how to get the function return value.
>>> Does pypy have this feature?
>>>
>>
>>
>> I think you need to use the function "pypy_execute_source_ptr", and pass
>> a pointer to a C variable.
>> From the Python side, it's turned into an int, that you can cast back to
>> a ffi pointer.
>> Something like this:
>>
>> import cffi
>> ffi = cffi.FFI()
>> result_ptr = ffi.cast('double *', c_argument)
>> result_ptr[0] = 42.0
>>
>> --
>> Amaury Forgeot d'Arc
>>
>
>


-- 
Amaury Forgeot d'Arc
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/pypy-dev/attachments/20150513/320e613b/attachment-0001.html>