Clear Filters
Clear Filters

Create an array of distinct objects of handle class

9 views (last 30 days)
I want to store objects of a handle class in an array.
When using
for i=1:2
arr(i) = uilabel;
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
Steven Lord on 19 Apr 2024 at 13:34
Why is the for loop not a desirable solution for you?
Michael on 19 Apr 2024 at 20:40
Because it is bulky, clutters the code and not very efficient.

Sign in to comment.

Accepted Answer

Bruno Luong
Bruno Luong on 19 Apr 2024 at 12:30
Edited: Bruno Luong on 19 Apr 2024 at 22:51
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";
Bruno Luong
Bruno Luong on 19 Apr 2024 at 13:48
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 on 19 Apr 2024 at 20:48
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.

Sign in to comment.

More Answers (1)

Fangjun Jiang
Fangjun Jiang on 19 Apr 2024 at 13:03
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.
Michael on 19 Apr 2024 at 20:44
Edited: Michael on 19 Apr 2024 at 20:45
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 on 19 Apr 2024 at 22:47
Edited: Bruno Luong on 19 Apr 2024 at 22:50
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.

Sign in to comment.


Find more on Customize Object Indexing in Help Center and File Exchange




Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!