MATLAB: How to call a nested function from a method

classoop

Hi,
I'm working on a OOP-Script and was wondering how nested functions in Methods behave.
I don't have a particular example yet, I just played around a little and coudn't make it work.
I imagine somethin like this: 
classdef example
    properties 
        one
        two
    end
    methods
        %Constructor
        function obj = example(1,2)
        obj.one = 1
        obj.two = 2
        end
        
        function parent(obj)
            X = 1 + child
            
            function child(obj)  
                [...]
            end
        end 
    end
end
I tried to call the "child" function from a different script to see it's value but always got errors like "no static Method or propertie" or "not enough input arguments"
I tried calling it like 
example.parent.child(1,2) 
example.child(1,2)
@example.child
and a couple other options.
My try and error progress got me thinking if this is even possible at all?
Any tipps and tricks are highly appreciated!

Best Answer

"how nested functions in Methods behave" the same way as in functions
"call the "child" function from a different script" the only way to call the nested function, child, from outside the method, parent, is by use of a function handle that is created inside the method, parent. There must be a good reason to use function handles this way, because it will come with surprises.
"is [it] even possible at all?" I recommend that you regard it as impossible.
"I want to Access the Value of a Child function that is NOT a Constructor..." A nested function cannot be a constructor. And a nested function inside a constructor cannot be reached from outside the constructor.
Here is a small demo based on your class, example.
>> obj = example( 1, 2 );   % create an object
>> [X,fh] = obj.parent      % call the method, parent
Nested function, child
X =
    20
fh =
  function_handle with value:
    @example.parent/child
>> fh()                     % call the nested function, child,
Nested function, child      % by means of the function handle, fh
ans =
    19
>>
>> obj.two = 20;            % assing 20 to the property, two
>> fh()                     % the new value of two does not
Nested function, child      % affect the value returned by fh()
ans =
    19
>>
where 
classdef example
    properties
        one
        two
    end
    methods
        % Constructor
        function obj = example( v1, v2 )
            obj.one = v1;
            obj.two = v2;
        end
        % Ordinary method
        function [X,fh] = parent(obj)     
            X = 1 + child;
            fh = @child;    % create function handle
            function val = child()        
                disp('Nested function, child')
                val = 17 + obj.two;
            end
        end
    end
end
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