ToString Method

I am not sure if I understand the question, but if I got it right, you are wondering why instances of type Form does not behave like instances of type ExtendedForm.

Overrides only replace the methods on objects that are of 'child' types, not the methods on the 'parents'. First of all, it's not how inheritance is supposed to work, but it's also not practically possible, i.e. what if you have two extended classes; which ToString override should be used?

The following should explain how it works.

 public class ClassBase { public override string ToString() { return "base"; } } public class ClassA : ClassBase { public override string ToString() { return "A"; } } public class ClassB : ClassBase { public override string ToString() { return "B"; } } public class ClassC : ClassA { // No override } 

This would produce the following

 ClassBase baseClass = new ClassBase(); baseClass.ToString() // Returns "base" ClassA aClass = new ClassA(); aClass.ToString(); // Returns "A" ClassB bClass = new ClassB(); bClass.ToString(); // returns "B" ClassC cClass = new ClassC(); cClass.ToString(); // returns "A" because no override exists 

Keep in mind that it does not matter what kind of reference you have. Say you have a reference to a ClassBase, which is actually referencing a ClassA, then the ClassA override would still be called

 ClassBase baseClass = new ClassA(); baseClass.ToString(); // Returns "A" because baseClass is actually a ClassA 

You don't see your new method because the Form class is not a SpecificForm class. Inheritance only moves in one direction. If your base type also took on the attributes of the child type, what would happen when two child types both add members with the same name?

You aren't being clear on what the problem is, code examples always help, but I will cover the two I can think of:

Form form = new Form(); form.ToString(); //returns FormProxy923a5e0e9d7a46b7baa4dfe2173af18c 

This is to be expected, as SpecificForm is not involved here.

Form form = new SpecificForm(); form.ToString(); //returns FormProxy923a5e0e9d7a46b7baa4dfe2173af18c 

This is likely caused by missing the override keyword in your ToString() definition, it should look like this:

public override string ToString() { //Do stuff } 

If you are missing the override the default behavior is to create a non-virtual method, which only affects variables of type SpecificForm in your example.

Not sure if I understood your question. If you are asking why this part:

return this.Description; 

doesn't execute instead of this part:

if (this.Description == null) return this.Form.ToString(); 

I can only say, "this.Description" was not set in your coding path before this part gets executed.