How to constrcut object array in a container class in matlab

Question

I have a class MyData and a class Container

classdef MyData < handle
    properties
        x
    end

    methods
        function obj=MyData()
            obj.x=0;
        end
    end
end

classdef Container < handle
    properties
        myobject_array
    end

    methods
        function obj=Container(n)
            obj.myobject_array(n)=MyData();
        end
    end
end

When I want to construct a Container object by Container(3), the following error is thrown

The following error occurred converting from MyData to double:
Conversion to double from MyData is not possible.

Error in Container (line 8)
            obj.myobject_array(n)=MyData();

How can I write the constructor of Container to make a array of MyData object be constructed in Container object?

Paolo · Accepted Answer · 2020-05-07 14:21:32Z

2

Change the Container constructor:

classdef Container < handle
    properties
        myobject_array
    end

    methods
        function obj = Container(n)
            MyObjectArray(n,1) = MyData;
            obj.myobject_array = MyObjectArray;
        end
    end
end

or:

classdef Container < handle
    properties
        myobject_array
    end

    methods
        function obj = Container(n)
            obj.myobject_array = MyData.empty;
            obj.myobject_array(n,1) = MyData();
        end
    end
end

>> c = Container(3);
>> c.myobject_array

ans = 

  3×1 MyData array with properties:

    x

edited May 7, 2020 at 14:21

answered May 7, 2020 at 14:01

Paolo

26.6k8 gold badges51 silver badges88 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Xu Hui Over a year ago

It works, sir, could you please tell me why we can not directly assign on obj.myobject_array? It seems that by defalut the obj.myobject_array is double. Can we told the matlab that the type of obj.myobject_array should be MyData?

Paolo Over a year ago

I believe the answer by @Cris addresses that.

Paolo Over a year ago

@XuHui I've also added another possible solution

Cris Luengo · Accepted Answer · 2020-05-07 14:17:40Z

1

Another solution is to provide a default value for the property:

classdef Container < handle
    properties
        myobject_array = MyData;
    end

    methods
        function obj=Container(n)
            obj.myobject_array(n) = MyData;
        end
    end
end

(Note that you do not need to provide empty parentheses, MyData is the same as MyData(). It is traditional in MATLAB to not add the empty parentheses.)

answered May 7, 2020 at 14:17

Cris Luengo

61.4k10 gold badges75 silver badges135 bronze badges

Collectives™ on Stack Overflow

How to constrcut object array in a container class in matlab

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related