How do you print out the value of a System::Classes::TWndMethod variable?

Question

If I have a variable that is of type System::Classes::TWndMethod, how can I print out the value with any of the *printf type functions using %p?

I tried casting to (void*) but the compiler failed with an internal error.

Basically, I have the WndProc of three TEdit fields that I'm overriding. They can all be handled the same, so I wanted to see if they all use the same WndProc (for the callback to original routine), which I presume they would, but would like to check before actually doing it.

Answer 1

You can't print out a TWndMethod as-is using %p, because it is not a single pointer, it is actually a struct which holds 2 pointers.

If you want to print them out, cast the TWndMethod to System::TMethod first:

The TMethod type stores the Code and Data pointers for a method. This type can be used in a type cast of a method pointer to access the code and data parts of the method pointer.

Then you can print out its Code and Data fields as needed, where:

• the Code field points at the class method itself

• the Data field points at the object which is passed to the method's hidden this parameter.

For example:

TWndMethod wm = ...;
TMethod &m = reinterpret_cast<TMethod&>(wm);
printf("%p %p\n", m.Code, m.Data);