How are method(obj) calls handled in MATLAB?

Now, as far as I can tell, calling obj.method or method(obj) seems to give the same results. However, when I tried to see how subsref behaves in these cases, I came to the startling realization that method(obj) doesn't seem to go through the subsref mechanism. So how are these calls then handled and is there a practical way to override them?

I'm trying to do this, so I can make something like method(object).otherMethod possible (which I would obviously be handling through a custom subsref). Any ideas?

(I also asked about this on StackOverflow)

Answer 1

[Sean de Wolski]

I would guess that it uses the metaclass function or ? equivalent.

obj = MyClass;
mc = metaclass(obj);
mc.MethodList

Equivalent to:

mc = ?MyClass;
mc.MethodList;

[Vladimir Peri]

Huh, not sure I follow what you mean here. In any case, I guess this means it's not possible to overload this behavior?

[Sean de Wolski]

I completely misunderstood what you were asking. I thought you were asking how:

methods(obj)

worked. There is a thread somewhere on the difference between obj.foo and foo(obj). I'll see if I can find it.

[Walter Roberson]

There was a recent thread that indicated that obj.method bypassed some checks that method(obj) would otherwise use.

Answer 2

[Matt J]

method(obj) is handled like any other function call. To enable the kind of syntax you're looking for, you could do something very similar to this

http://www.mathworks.com/matlabcentral/fileexchange/26570-direct-indexing-of-function-calls-oop-exercise

but I doubt it's worth it.

Incidentally, obj.method does not (always) go through subsref either. Even if your class defines a subsref method, when you invoke obj.method from within the classdef, subsref is not called. Inside the classdef, obj.method is entirely equivalent to method(obj).