[Mono-list] cannot assign to <this> problem

[Artur Karazniewicz]

Hello,

I'm new to C# but I've coded a lot in C++ and
I'm trying implement Visitor pattern
in C# - and i'm not sure how to get double
dispatch mechanism to work with C#.

Example:
I'm going to implement Visitor which changes
some things in visited object. In C++ right
way to do so is:

// C++
class Visitor {

	void Visit( Foo& aFoo ) {
		aFoo.SetSomething( "something" );
	}

}

class Foo {

	void Accept( Visitor& aVisitor ) {
		aVisitor.Accept( *this );
	}

}
//

// it works fine but in C# code like this:


// C#
class Visitor {

	void Visit( ref Foo aFoo ) {
		aFoo.SetSomething( "something" );
	}

}

class Foo {

	void Accept( Visitor aVisitor ) {
		aVisitor.Accept( ref this );
	}

}

fails during compilation with message:

error CS1604: Cannot assign to `this'.

I dont know - how can I implement such kind
of double dispatch in C#???

regards
Artur.