Create an array of distinct objects of handle class

I want to store objects of a handle class in an array.

When using

for i=1:2

arr(i) = uilabel;

end

arrFor(1).Text = "textFor 1";

arr(2).Text = "textFor 2";

the objects in the array are distinct.

When using

arrDir(1:2) = uilabel;

arrDir(1).Text = "textDir 1";

arrDir(2).Text = "textDir 2";

both text will change to "textDir 2" which makes sense because uilabel is a handle class.

What is the syntax to avoid the for loop and diretly crating an array of distinct objects of a handle class?

[Steven Lord]

Why is the for loop not a desirable solution for you?

[Michael]

Because it is bulky, clutters the code and not very efficient.

Answer 1

[Bruno Luong]

Why not simply calling the constructor as many time as you need

arrDir = arrayfun(@(~)uilabel, 1:2);
arrDir(1).Text = "textDir 1";
arrDir(2).Text = "textDir 2";
arrDir(1).Text

[Michael]

Thank you.

I am aware of that solution but want to avoid it as well. This is basically the same as the for loop but in a more compact form.

Is there another possibility to use a more 'native' assignment?

[Bruno Luong]

Well here is, lust a longer and longer code

copyhandle = @(h,varargin) arrayfun(@(~)copy(h), zeros(varargin{:}))

h = uilabel();
arrDir = copyhandle(h, 1, 2); % copy h to an array of size 1 x 2

arrDir(1).Text = "textDir 1";
arrDir(2).Text = "textDir 2";
arrDir(1).Text

[Bruno Luong]

You could probably declare a subclass and over load the subsref subsasg methods and erase the handle copy behavior.

First of all I never did such thing. Second: it is just adding layer on layer and tweak the initial design pattern. It become dirty diffuclt to maibtain understand the code.

[Michael]

Under the hood this is basically the same thing as the for loop with the drawback of more difficult debugging but more compact code. Regarding the other answers this seem to be the best option. Thank you.

Answer 2

[Fangjun Jiang]

As long as uilable() can only create a single object, there is no way to avoid the loop.

In arrDir(1:2) = uilabel, the same single handle was assigned to the two elements of arrDir.

What you should look for, is whatever the object class that you are working on, whether its creation method has the capability or syntax to create multiple objects in one shot.

[Matt J]

As long as uilable() can only create a single object, there is no way to avoid the loop.

And there is no way for a handle class constructor to create multiple instances. So, all solutions will be loop-equivalent.

[Michael]

This answers the question. It is not what I hoped but in that case arrayfun seems to be the cleanest way to handle this case.

Do you know why there is no such functionality? Seems like there might be plenty of usecases where this could be really helpful, especially when dealing with user interfaces.

Is there some underlying Matlab voodoo why this does not male sense?

[Bruno Luong]

Well a lot pf people use object (graphical) handles for decades, I don't see that often the need of deep copying handls or clonig them to an array.

If they do often the constructor is invoked as many as it needs, whereas it is manually unroll out, inside a for-loop or wrapped into an arrayfun/cellfun.