Neal Becker <ndbeck...@gmail.com> writes:
> I assume overload resolution extends to scoring multiple arguments as well?
>
Sure. This is the reason that scores are optional<unsigned>. If any
single argument scorer returns optional<unsigned>() (meaning 'unsuitable'),
this stops evaluation and kills the score for the entire signature.
Here are some excerpts from the test suites:
//------------------------------------------------------
std::string f1(float, bool) { return "float,bool"; }
std::string f2(float, int) { return "float,int"; }
std::string f3(float, std::string) { return "float,std::string"; }
BOOST_PYTHON_MODULE(ambig6_ext)
{
def("f", &f1);
def("f", &f2);
def("f", &f3);
}
//------------------------------------------------------
>>> from ambig6_ext import f
>>> help(f)
Help on built-in function f:
f(...)
f( (float)arg1, (bool)arg2) -> str :
C++ signature :
std::string f(float,bool)
f( (float)arg1, (int)arg2) -> str :
C++ signature :
std::string f(float,int)
f( (float)arg1, (str)arg2) -> str :
C++ signature :
std::string f(float,std::string)
>>> f(1.0, True) # perfect match, score 0
'float,bool'
>>> f(1.0, 1) # perfect match, score 0
'float,int'
>>> f(True, True) # best match arg1 score is 1, arg2 score is 0
'float,bool'
#
# Here, note that f3 is not listed in the set of ambiguous candidates,
# as the arg2 score (conversion of float to string) is 'unsuitable' and
# removes it from consideration
#
>>> f(1.0,1.0) # ambiguous, f1 & f2 both score 1
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
Boost.Python.AmbiguousCall: Ambiguous call to Boost.Python function ambig6_ext.f
C++ signatures:
f(float, int)
f(float, bool)
#
# If the second arg is a string, then the 3rd overload
# always matches...
#
>>> f(True, 'helloverloading') # best match, score 1
'float,std::string'
>>> f(1, 'helloverloading') # best match, score 1
'float,std::string'
>>> f(1.0, 'helloverloading') # perfect match, score 0
'float,std::string'
#
# ... Unless the arg1 is also a string. Note this one is ArgumentError,
# listing all overloads, not AmbiguousCall listing the ambig. ones.
#
>>> f('uh', 'oh') # all overloads score 'unsuitable'
Boost.Python.ArgumentError: Python argument types in
ambig6_ext.f(str, str)
did not match C++ signature:
f(float, std::string)
f(float, int)
f(float, bool)
-t
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