Problem with partial method C# 3.0

Answer 1

You should get error CS0759. Test case:

partial class MyClass
{
    partial void MyMethod()
    {
        Console.WriteLine("Ow");
    }
}

partial class MyClass
{
    partial void MyMethod2();
}

Compilation results:

Test.cs(6,18): error CS0759: No defining declaration found for implementing 
declaration of partial method 'MyClass.MyMethod()'

Does that not do what you want it to?

Answer 2

In short, no; that is the point of partial methods - the declaring code doesn't need to know whether an implementation is provided or not.

Of course - you could just not declare the partial method: consume it assuming it exists; if you don't provide it, the compiler will complain of a missing method.

There is a hacky way to check at runtime (with partial methods), which is to have the other half update a ref variable:

partial void Foo(ref chk);

partial void Foo(ref chk) { chk++;}

(and verify it changes) - but in general, partial methods are designed to not know if they are called.

Another approach is a base-class with an abstract method - then it is forced by the compiler to be implemented.

Answer 3

This is the whole purpose of partial methods. If the method is not implemented, it is removed without a trace, and without a warning.

One solution to this type of problem would be to use a double derived pattern in your code generation. This is used extensively by DSLTools and is quite powerful.

Write the following code by hand :

public class MyClassBase
{
    public abstract void MyMethod();
    //Put all other methods required by the class here.
}

public partial class MyClass : MyClassBase
{
   //This class is entirely empty! 
}

Generate the following code in magic.

public partial class MyClass
{
    public void MyMethod(){}
}

If someone fails to implememnt MyMythod() in the generated code, you will get a compiler error.