How to make switch case in between different classes in matlab?

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kanuri venkata mohana 2020-7-8

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评论： kanuri venkata mohana 2020-7-23

Hi guys,

I have a small question regarding switch case. Iam doing my project using Matlab OOP. Is it possible to make switch case using classes? for example

clMatcore is my super class and clSteel clNano and clIron are my subclasses. I created all the classes and functions for them. Is it possible to make a switch case between them. I was a bit confused in this. Could someone help me out if possible with a small example.

Thankyou

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Steven Lord 2020-7-8

It's not clear to me what your goal is in using a "switch case using classes". Can you describe (in words not code) what your goal is in selecting between steel, nano, and iron? What problem are you trying to solve?

kanuri venkata mohana 2020-7-8

Hi Steven, Thank you for your reply. Here my goal is , i have different materials for my core which are made up of steel, nano, iron. I need to choose my material according to my usage. So i created each class for each material. Now i have to make them in a way, that i can use them according to my design of transformer.

Thankyou..

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Answer 1

Steven Lord 2020-7-9

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Something like:

switch material
    case "steel"
        x = clSteel;
    case "iron"
        x = clIron;
    otherwise
        error("I don't know how to make a transformer core out of " + material)
end

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Steven Lord 2020-7-23

编辑：Steven Lord 2020-7-23

在 MATLAB Online 中打开

Write a function makeMaterial, something like:

function x = makeMaterial(material)
switch material
    case "air"
        x = clAircore;
    case "steel"
        x = clSisteel;
    % etc with the other cases
    otherwise
        error("I don't know how to make a transformer core out of " + material)
end

If your class names had a pattern, always "cl" followed by the material followed by "core", you could do something like this that would be able to recognize new subclasses using class introspection (untested):

function x = makeMaterial(material)
subclassname = "cl" + material + "core";
S = meta.class.fromName(subclassname);
if S < ?clmaterialcore % it is a subclass of clmaterialcore
    constructor = str2func(subclassname);
    x = constructor();
else
    error("I don't know what material " + material + " is.")
end

In your class diagram, you have a lot of inheritance, some of which seems a bit off to me. For instance, can a clmaterialcore object be substituted for a clCore object or does a clCore have a clmaterialcore? Do you want composition or inheritance?

Steven Lord 2020-7-23

在 MATLAB Online 中打开

Inheritance doesn't seem to be the right approach for some of the classes in your hierarchy.

If I were to plug in a clmaterialcore into a function that expects a clCore, should that function work? If not, clmaterialcore should not be a subclass of clCore.

If I were to plug in a clCore into a function that expects a clmaterialcore, should that function work? If not, clCore should not be a subclass of clmaterialcore.

To me, a mental model where a clCore has a clmaterialcore as one of its properties seems more natural.

classdef clCore
    properties
        composition % what the core is made of
    end
end

Use as:

s = clSteel;
% Build a core.
C = clCore(whateverInputsAreNeededToBuildAclCore);
% Make the core out of steel.
% You probably want to specify this in the constructor call.
C.composition = s;
% Have the core ask its material about the material's conductivity.
C.composition.conductivity

kanuri venkata mohana 2020-7-23

Thankyou for your reply Steven i will check with this idea again. I could make switch case with classes as you suggested but, clmaterialcore as input to clCore is not being possible according to my classes. SO i made clmaterialcore as parent class. It worked but it is in reverse order of my Tree diagram.

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