#146 [python] more helpful error msg when overload lookup fails

[Tijs Michels]

Short explanation:

In Python, instead of the scarcely helpful error message

NotImplementedError: No matching function for
overloaded 'Foo_setCoord'

print

NotImplementedError: Wrong number of arguments for
overloaded function 'Foo_setCoord'.
Possible prototypes are:
self.setCoord(int,int) # Foo *self,int x,int y
self.setCoord(int) # Foo *self,int x

Long explanation:

Currently, if you wrap the following class

class Foo {
private:
int X, Y;
public:
Foo(int id);
Foo(const char *name);
void setCoord(int x, int y);
void setCoord(int x);
};

and you say
f = Foo( 1, 2 )
the dispatcher function generates this error message:

NotImplementedError: No matching function for
overloaded 'new_Foo'

This is hardly helpful. With this patch you get:

NotImplementedError: Wrong number of arguments for
overloaded function 'new_Foo'.
Possible prototypes are:
Foo(int) # int id
Foo(char const *) # char const *name

Similarly, if you say
f.setCoord( 1, 2, 3)
you currently get

NotImplementedError: No matching function for
overloaded 'Foo_setCoord'

whereas

NotImplementedError: Wrong number of arguments for
overloaded function 'Foo_setCoord'.
Possible prototypes are:
self.setCoord(int,int) # Foo *self,int x,int y
self.setCoord(int) # Foo *self,int x

might help users of the extension module more.

Note that this patch only applies to a wrong number of
arguments. For the other case (correct number of
arguments, but at least one of them is of a wrong type)
the error message is already very detailed and helpful.

[Tijs Michels]

Logged In: YES
user_id=1259995

With the latest patch the output has less redundancy, and
also includes the return type.

NotImplementedError: Wrong number of arguments for
overloaded function 'setCoord'.
Possible prototypes are:
void Foo.setCoord(int,int) # self, x, y
void Foo.setCoord(int) # self, x

This version splits the string over multiple lines, as some
compilers (notably MSVC) impose a maximum on the source code
line length.

[Tijs Michels]

small patch against python.cxx,v 1.203