How does MATLAB resolve a function handle with multiple levels of indexing

Imagine that I have classes class1 and class2 and that class2 has a property parent that points to an instance of class1. Class1 has a function called myFunction. Both classes are handle classes. If I set a callback on a uitable in an old style figure (not sure if that is relevant), I get different behavior between the following and I'm curious why.

Approach 1 (in class2) - this doesn't work

h_table.Callback = @obj.parent.myFunction;

Approach 2 - this works

p = obj.parent;
h_table.Callback = @p.myFunction

What's going on here?

I think this works as well although I haven't tested it

Approach 3 - works? (haven't tested)

h_table.Callback = @(a,b)obj.parent.myFunction(a,b);

Why does Approach 1 not work?

I'll note that if you look at the function handle using:

fh = @obj.parent.myFunction; % for fh = @p.myFunction
s = functions(fh)

The resulting structure and info is very different.

For 1 I see: (roughly, modified from actual class names but I think this is accurate)

function: 'obj.parent.myFunction'
type: 'classsimple'
file: ''
class: 'b'

For 2 I see: (again, roughly)

function: '@(varargin)p.myFunction(varargin{:})'
type: 'anonymous'
file: 'b.m'
workspace: {[1×1 struct]}
within_file_path: ''

Answer 1

[Matt J]

Well, ultimately I think Approach 3 is the only 'correct' one. It appears that when the indexing is one level deep (as in Approach 2), Matlab assumes you are trying to build an anonymous function and appends a generic parameter list as a convenience. Otherwise, though, it doesn't know what you want, as demonstrated below.

obj=myclass;
f=@obj.func

f = function_handle with value:
    @(varargin)obj.func(varargin{:})

s.obj=obj;
f=@s.obj.func

f = function_handle with value:
    @s.obj.func

I think it's undocumented.

[Jim Hokanson]

Yeah, my impression is that this is undocumented behavior. I'm not a function handle expert though and thought maybe this was obvious to someone else.