[Ironpython-users] How to call parameterless overload of generic method?

[Markus Schaber]

Hi,

The attached C# file demonstrates a small problem we currently encountered 
using IronPython 2.7.4:

We have a C# method which has two overloads - one is parameterless, and the 
other one has a single out parameter.

For non-generic methods, it is possible to call both variants when calling with 
and without clr.Reference, but this does not work for generic methods.

When trying to call the parameterless generic method directly, the following 
exception appears:

Microsoft.Scripting.ArgumentTypeException was unhandled
  HResult=-2146233088
  Message=Multiple targets could match: Method(), Method()
  Source=Microsoft.Dynamic
  StackTrace:
[snipped]

The workaround is to use the .Overloads[] syntax:

print instance.Method[str].Overloads[()]()


Btw, trying "print instance.Method[str].Overloads[int]()" leads to the 
following funny ArgumentTypeException: "Method() takes at least 2147483647 
arguments (0 given)"



Best regards

Markus Schaber

CODESYS® a trademark of 3S-Smart Software Solutions GmbH

Inspiring Automation Solutions

3S-Smart Software Solutions GmbH
Dipl.-Inf. Markus Schaber | Product Development Core Technology
Memminger Str. 151 | 87439 Kempten | Germany
Tel. +49-831-54031-979 | Fax +49-831-54031-50

E-Mail: m.scha...@codesys.com | Web: http://www.codesys.com | CODESYS store: 
http://store.codesys.com
CODESYS forum: http://forum.codesys.com

Managing Directors: Dipl.Inf. Dieter Hess, Dipl.Inf. Manfred Werner | Trade 
register: Kempten HRB 6186 | Tax ID No.: DE 167014915

This e-mail may contain confidential and/or privileged information. If you are 
not the intended recipient (or have received
this e-mail in error) please notify the sender immediately and destroy this 
e-mail. Any unauthorised copying, disclosure
or distribution of the material in this e-mail is strictly forbidden.


namespace AmbigousCall
{
        using System;

        using IronPython.Hosting;

        using Microsoft.Scripting.Hosting;

        class Program
        {
                const string SRC = @"
import clr
print instance.Plain()

print instance.Plain(clr.Reference[int]())

print instance.Method[str](clr.Reference[int]())

print instance.Method[str]()
";
                static void Main(string[] args)
                {
                        ScriptEngine engine = Python.CreateEngine();
                        ScriptScope mainScope = engine.CreateScope();

                        mainScope.SetVariable("instance", new TwoMinded());

                        engine.Execute(SRC, mainScope);

                        Console.ReadLine();
                }
        }

        public class TwoMinded
        {
                public int Plain() { return 1; }

                public int Plain(out int anotherInt)
                {
                        anotherInt = 2;
                        return 3;
                }

                public T Method<T>() { return default(T); }

                public T Method<T>(out int anotherInt)
                {
                        anotherInt = 0;
                        return default(T);
                }
        }
}

_______________________________________________
Ironpython-users mailing list
Ironpython-users@python.org
https://mail.python.org/mailman/listinfo/ironpython-users