How to create an object using class name

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

Answer 1

[Matt J]

function newObj = createNewObject(obj)                   
    newObj = feval( class(obj) ); 
end

[Sylvain]

Thank you,

one of the answer bellow mention eval rather than feval. Can anyone clarify the difference?

[Matt J]

feval doesn't suffer from the problems cited here,

https://www.mathworks.com/help/matlab/matlab_prog/string-evaluation.html?s_tid=answers_rc2-1_p4_Topic

[Sylvain]

Thank you, very instructive

Answer 2

[Sky Sartorius]

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

Answer 3

[Image Analyst]

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)     

[Matt J]

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.