[Boost-bugs] [Boost C++ Libraries] #3710: error incorrect when calling boost::python function via functools.partial

Subject: [Boost-bugs] [Boost C++ Libraries] #3710: error incorrect when calling boost::python function via functools.partial
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-12-03 18:54:50

#3710: error incorrect when calling boost::python function via functools.partial
--------------------------+-------------------------------------------------
 Reporter:  anonymous     |       Owner:  dave   
     Type:  Bugs          |      Status:  new    
Milestone:  Boost 1.42.0  |   Component:  Python 
  Version:  Boost 1.41.0  |    Severity:  Problem
 Keywords:                |  
--------------------------+-------------------------------------------------
 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.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3710>
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