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Create an array of distinct objects of handle class

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Michael
Michael el 19 de Abr. de 2024
Editada: Bruno Luong el 19 de Abr. de 2024
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?
  2 comentarios
Steven Lord
Steven Lord el 19 de Abr. de 2024
Why is the for loop not a desirable solution for you?
Michael
Michael el 19 de Abr. de 2024
Because it is bulky, clutters the code and not very efficient.

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Bruno Luong
Bruno Luong el 19 de Abr. de 2024
Editada: Bruno Luong el 19 de Abr. de 2024
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
  4 comentarios
Bruno Luong
Bruno Luong el 19 de Abr. de 2024
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
Michael el 19 de Abr. de 2024
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.

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Más respuestas (1)

Fangjun Jiang
Fangjun Jiang el 19 de Abr. de 2024
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.
  3 comentarios
Michael
Michael el 19 de Abr. de 2024
Editada: Michael el 19 de Abr. de 2024
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
Bruno Luong el 19 de Abr. de 2024
Editada: Bruno Luong el 19 de Abr. de 2024
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.

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