How can I get rid of this enumeration error while using classes?

Here's an example of what I am trying to do:

 classdef Colors

    properties
        R = 0; 
        G = O;
        B = 0;
    end

    methods
        function c = Colors(r , g, b)
            c.R = r; c.G = g; c.B = b; 
        end
    end

    enumeration
        Red    (1, 0, 0)
        Orange (1,.5, 0)
        Yellow (1, 1, 0)
        Green  (0, 1, 0)
        Blue   (0, 0, 1)
        Indigo (.2,0,.8)
        Violet (1, 0, 1)
    end  
end

>> c = Colors.Red

??? Error using ==> Colors

Attempt to define enumeration without Enumeration class attribute in class 'Colors'.

[Captain Karnage]

Perhaps it's because it's an old question and something you did was not supported in R2013. But in R2022b your code now works, with one exception: You have G = O (the letter O) when it should be G = 0 (zero).

Answer 1

[Bradley Stiritz]

MATLAB enumeration definitions can't be nested within another classdef definition, as your code attempts to do. That would be very convenient & useful, but unfortunately isn't supported currently.

You need to define your enumeration as its own class in its own @-folder. Also, note that since you've supplied your own enumeration values, your class needs to inherit support for those values. However, your numeric vector values aren't specified properly; they need to be within brackets. Here's how your classdef would need to look.. (I'm only showing the first few rows)

classdef MyColors < double

   enumeration
        Red    ([1, 0, 0])
        Orange ([1,.5, 0])
        Yellow ([1, 1, 0])
    end  

end

Unfortunately, when we try to use this, we find that vector values aren't allowed :(

>> MyColors.Red
In class 'MyColors', enumeration member named 'Red' must be scalar.

So you'll have to find a different way to implement your idea. I would suggest considering an ordinary classdef with constant properties, a la :

classdef MyColors

   properties (Constant)
        Red    = [1, 0, 0];
        Orange = [1,.5, 0];
        Yellow = [1, 1, 0];
    end  

end

Now we get our desired results:

>> MyColors.Red  
ans =
     1     0     0

[Milan]

Matlab really has its own way to copy OOL which challenge all logic and common sense.