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How to create an object using class name

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Sylvain
Sylvain on 18 Feb 2020
Commented: Sylvain on 21 Feb 2020
In my function, I am getting the class name from an object to create a new one. What is the right syntax to creat the new Object ?
function newObj = createNewObject(obj)
className = class(obj);
newObj = className();
end

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Accepted Answer

Matt J
Matt J on 18 Feb 2020
function newObj = createNewObject(obj)
newObj = feval( class(obj) );
end

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Sylvain
Sylvain on 20 Feb 2020
Thank you,
one of the answer bellow mention eval rather than feval. Can anyone clarify the difference?
Sylvain
Sylvain on 21 Feb 2020
Thank you, very instructive

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More Answers (2)

Sky Sartorius
Sky Sartorius on 18 Feb 2020
A quick and dirty approach that will work in many cases is to use eval:
function new = createNewObjectOfThisClass(original)
new = eval([class(original) '.empty;']);
end

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Image Analyst
Image Analyst on 18 Feb 2020
That won't work for all types of objects, like structures, other custom-designed classes, etc. I think your best bet is to just make a copy of the variable
function newObj = createNewObject(obj)
newObj = obj;
end
It will have the values of the input object, but more importantly, it will inherit all the fields, properties, and methods of your input class. As you can see you actually don't even need this function at all since it's just a wrapper than essentially does nothing. You could just simply do this
newObj = obj;
rather than this
newObj = createNewObject(obj)

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Matt J
Matt J on 18 Feb 2020
I disagree. It's often necessary to call the constructor to instantiate a new, independent version of the original object. For example, if obj is an object of a handle class then
newObj = obj
does not give you an indepedent copy of obj. Just another handle to its property data.

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