C# Language Specification

this access

A nested type and its containing type do not have a special relationship with regard to this-access (§7.6.7). Specifically, this within a nested type cannot be used to refer to instance members of the containing type. In cases where a nested type needs access to the instance members of its containing type, access can be provided by providing the this for the instance of the containing type as a constructor argument for the nested type. The following example

using System;

class C
{
int i = 123;

public void F() {

Nested n = new Nested(this);
n.G();
}

public class Nested

{
C this_c;

public Nested(C c) {

this_c = c;
}

public void G() {

Console.WriteLine(this_c.i);
}
}
}

class Test

{
static void Main() {
C c = new C();
c.F();
}
}

shows this technique. An instance of C creates an instance of Nested and passes its own this to Nested’s constructor in order to provide subsequent access to C’s instance members.

5.