Overloaded method defined in class definition, not working

Hi all,

I defined a method 'find' in a class definition('tree'). Upon doing 'help find' I can see it under the Overloaded Methods heading ('tree/find'). But when I try to use it MATLAB gives me error saying "Method 'find' is not defined for class 'tree' or is removed from MATLAB's search path." Would anyone have any idea what the problem might be? Thanks.

[Geoff Hayes]

Muhammad - how have you defined your class (with classdef property in file, or another way using the @), how have you defined the find method, and how are you invoking it?

[Muhammad Aneeq uz Zaman]

Hi Geoff, I have defined my class in a file with classdef, not in a @-file. I defined the find method in the file, just like the other methods (function I = find(obj, f))

[Geoff Hayes]

If I define a very simple class like

 classdef MyClass
   properties (Access=private)
      data;
   end
     methods
        function obj = MyClass(n)
           obj.data = randi(255,n,1);
        end

        %FIND   Returns index into data if f is found in data
        function r = find(obj,f)
           r = find(obj.data==f);
        end

        function d = get(obj)
            d = obj.data;
        end

     end
 end

I am able to make use of the find function as

 myObj = MyClass(42);
 myObj.find(111)

The result is either an empty matrix (if 111 is not an element within the data array member of the instance), or the index of 111 in the array.

Are you doing something similar?

[Muhammad Aneeq uz Zaman]

Hi, this is some of my classdef file. I think I do exactly as you did but for some inexplicable reason it doesn't work.

    classdef tree

    properties (SetAccess = private)
        Node = [];

        Parent = [ 0 ];

    end

    methods

        function [obj] = tree(content)

            obj.Node = content;
            root_ID = 1;

        end

        function I = find(obj, f)

            val = obj.Node ;
            I = strmatch(f',val');
        end

    end

    end

And I use it as

    t.find(t, 2) or t.find( 2)

Gives me "Error using tree/find Method 'find' is not defined for class 'tree' or is removed from MATLAB's search path."

Answer 1

[per isakson]

I made a classdef-file according to you description. It works as expected (R2013a).

    >> t= cssm_tree
    t = 
      cssm_tree with no properties.
    >> t.find('abc')
    cssm_tree/find
    ans =
        17
    >> help find
      ....
      Overloaded methods:
         tree/find
         mtree/find
         cssm_tree/find
         ...

where

    classdef    cssm_tree < handle
        methods
            function    ix = find( this, f )
                % find is overloaded 
                disp( 'cssm_tree/find' )
                ix = 17;
            end
        end
    end

Answer 2

[Muhammad Aneeq uz Zaman]

Ok I restarted MATLAB and for some weird reason, its working. Thanks for the help guys.

[Geoff Hayes]

I wonder if you had made changes to the class definition without deleting/clearing any instances of the class in the workspace, and then tried to use that instance again. For example, if I take your tree class as is and create an instance as

 t = tree(1);
 t.find(1)

I get the "correct" answer of

 ans =
     1

If I then comment out the find function in the tree class (and save the changes), and try again

 t.find(1)

I observe the error

 Error using tree/find
 Method 'find' is not defined for class 'tree' or is removed from MATLAB's  
 search path.

Since you restarted and everything worked okay, then perhaps in the future if you make changes to the class definition file (if that was the problem?) then always remember to clear any local variables that are instances of that class. Sometimes you are reminded of this by MATLAB (especially when you add functionality) with the

Warning: The class file for 'tree' has been changed, but the change cannot be applied because objects based on the old class file still exist. If you use those objects, you might get unexpected results. You can use the 'clear' command to remove those objects. See 'help clear' for information on how to remove those objects.