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matlabclassobjectmethods
Stephen Jeffress
Stephen Jeffress

Reputation: 21

In MATLAB classdef, can you define an "any_function"?

In MATLAB 's classdef, can you define a method that executes any_function that has called it?

For example, say I have defined this custom class type in MATLAB:

classdef custfloat

    properties
      value = double(0);   % Double value
    end

    methods


        function obj = custfloat(v, ex, mant)

            obj.value = ........blah blah blah;
        end


        function v = any_function(arg1,arg2)

            v = any_function(arg1.value, arg2.value);
        end

    end
end

So as long as any_function is defined for two doubles, it will work, no matter what any_function actually is.

Does this makes sense?

Upvotes: 2

Views: 195

Answers (1)

Sam Roberts
Sam Roberts

Reputation: 24127

I'm not sure what your question means exactly, but I think you can get what you're looking for my just subclassing double.

For example, here's a simple class that extends double to create something that's like double, but has a unit as well (for example metres or seconds).

classdef custDouble < double

    properties

        unit

    end

    methods

        function obj = custDouble(v, u)
            % Do something with exponents and mantissas instead if you like,
            % I can't remember floating point stuff well enough for this
            % example
            obj = obj@double(v);
            obj.unit = u;
        end

        function val = myExtraMethod(obj)

            val = custDouble(obj*2, obj.unit);

        end

    end

end

You can now create a custDouble like this:

>>a = custDouble(2, 'm')
a = 
  custDouble with properties:

    unit: 'm'
  double data:
     2

You can call your extra methods:

>> b=a.myExtraMethod
b = 
  custDouble with properties:

    unit: 'm'
  double data:
     4

and you can call any regular function that applies to doubles:

>> sqrt(a)
ans =
       1.4142

Note, though, that sqrt here will return a double, not a custDouble - it's just acting on the underlying double. If you wanted regular functions like sqrt to return a custDouble, you'd need to overload them with a method on custDouble that would behave in the appropriate way (such as, for example, calling builtin('sqrt',...) on the underlying double, then constructing the right unit, then putting them together into a custDouble - in the way that myExtraMethod above does).

Search the documentation for "Subclassing MATLAB Built-In Types" for more information.

Upvotes: 1

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