How to do OOP with Pascal?

Answer 1

I can't answer your question but I suggest to learn OOP with a language like Python or Groovy. Pascal isn't really something on which you'll be able to build a career. I'd rather suggest that as a third or fourth language to give you some ideas how other languages work but not as your first/main language.

Both offer an interactive console (for Python, I suggest iPython) where you can do small experiments.

Answer 2

That appears to be some nonstandard extension. The implementation of the function in question is:

function FooParent.Baz (b, a, z: Char) = s: Str100;
begin
  WriteStr (s, 'FooParent.Baz (', b, ', ', a, ', ', z, ')')
end;

Normally in Pascal, the name of the function is used as the function return variable, so the above function would be written like this:

function FooParent.Baz (b, a, z: Char): Str100;
begin
  WriteStr (Baz, 'FooParent.Baz (', b, ', ', a, ', ', z, ')')
end;

It appears that the = s syntax indicates that the return value of the function is stored in the variable s inside the function body. I'm not sure why that would need to be exposed in the object interface, though.