id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
3710	error incorrect when calling boost::python function via functools.partial	anonymous	troy d. straszheim	"Neal Becker wrote:
> Has anyone noticed that a function created with boost::python using
> args() to give keyword arguments doesn't seem to work with functools.partial keyword arguments (but does with positional args)?
>
> For example, I have this function:
>   class_<boost_uniform_real_wrap>
>     (""uniform_real"", ""Uniform float distribution"", bp::init<rng_t&,double,double>(
>     (bp::arg (""rng""),
>      bp::arg (""min""),
>      bp::arg (""max""))...
>
> Then:
> from functools import partial
> f = partial (uniform_real, rng=rng1) << using keyword doesn't work
> f (1,2)
> ArgumentError: Python argument types in
>     uniform_real.__init__(uniform_real, int, int)
> did not match C++ signature:
>     __init__(_object*, boost::random::mersenne_twister<unsigned int, 32, 624, 397, 31, 2567483615u, 11, 7, 2636928640u, 15, 4022730752u, 18, 3346425566u> {lvalue} rng, double min, double max)
>
> But this works:
> from functools import partial
> f = partial (uniform_real, rng1) << pos arg does work
>
> In [27]: f(1,2)
> Out[27]: uniform_real(1,2)
>

That doesn't work for pure python functions either:

>>> def f(x,y,z): return x*100 + y*10 + z
...
>>> from functools import partial as p
>>> p(f,x=1)(2,3)
Traceback (most recent call last):
  File ""<stdin>"", line 1, in <module>
TypeError: f() got multiple values for keyword argument 'x'
>>> p(f,x=1)(y=2,z=3)
123
>>> p(f,1)(2,3)
123

The error message is misleading for sure.  Boost.python is going through a list of overloads and trying them in order; if it runs out of overloads, it says nothing matched."	Bugs	new	Boost 1.42.0	python USE GITHUB	Boost 1.41.0	Problem