Problem calling explicit interface methods


#1

Hello,

I am trying to call explicitly implemented interface method, but get
such error
undefined method `bar’ for #App::Cls:0x000005c

C# code:

public interface IFoo
{
    void Bar();
}

public class Cls : IFoo
{
    void IFoo.Bar() { }
}

Ruby code:
x = App::Cls.new
x.bar

But this one works fine:

public class Cls : IFoo
{
    public void Bar() { }
}

What is wrong?

  • Alex

#2

Filed bug #23494.

Tomas


#3

Curious, how it is expected to work (or nobody thinked it over yet?)

Example to consider:

- - - -
public interface IFoo1
{
    void Bar();
}

public interface IFoo2
{
    void Bar();
}

public class Cls : IFoo1, IFoo2
{
    void IFoo1.Bar() {}
    void IFoo2.Bar() {}
    public void Bar() {}
}
- - - -

C# approach:
- - - -
Cls obj = new Cls();
obj.Bar();
((IFoo1)obj).Bar();
((IFoo2)obj).Bar();
- - - -

What is for IronRuby?

Thanks,

  • Alex

#4

I’m not convinced this is exactly a bug. There is no public ‘bar’
method on Cls after all. I think IronPython would require you to say
something like App::IFoo::bar(App::Cls.new()) in order to make the
interface call explicit.


#5

Not yet.

obj.as(IFoo1).Bar() might be one option.

Tomas


#6

Fair enough, it could be called a feature :slight_smile: There needs to be some way
how to call the method.

Tomas


#7

In IronPython, we went back and forth over this. On the one hand, the
API author might have chosen to make it harder to access the method,
requiring a cast like this:
App::Cls cls = new App::Cls();
cls.bar(); // syntax error
IFoo ifoo = (IFoo)cls;
ifoo.bar(); // works
OTOH, dynamic languages have no type for variables, and so you don’t
know if it should be an error or not. ie. How would IronRuby know if the
programmer expects a variable to be of type App::Cls or of type IFoo.

IronPython ended up allowing it as long as there was no clash. If there
is a clash, you have to use App::IFoo(cls).bar().

Thanks,
Shri