How to avoid using eval in this case?

5 views (last 30 days)
Hi, I read in multiple threads that the usage of the function eval should be avoided as much as possible. But in the following case I couldn't find a neater way to do so. I have a uicontrol function, and I have several buttons that will set different variables in a similar way. The code is somewhat like below:
w = -1;
h = -1;
editW = uicontrol('Style','edit');
buttonW = uicontrol('Style','pushbutton');
editH = uicontrol('Style','edit');
buttonH = uicontrol('Style','pushbutton');
In total I have more than 5 pushbuttons, each set a specific variable to what is written in the associated edit field. One way to write the callback functions is:
buttonW.Callback = @setW;
buttonH.Callback = @setH;
function setW(hObject,eventData)
w = str2double(editW.String);
end
function setH(hObject,eventData)
h = str2double(editH.String);
end
In this way, I will have to write more than 5 callback functions, which they are simply doing very similar things, making the code look very redundant. So I was thinking using the eval function:
buttonW.Callback = {@setVariable,'w'};
buttonH.Callback = {@setVariable,'h'};
function setVariable(hObject,eventData,input)
% Grab the associated edit field
edit = eval(['edit',upper(input)]);
x = str2double(edit.String);
eval([input '= x']);
end
In this way, I only need to define the function once. Is there other way to somewhat achieve the same effect without using the eval function?
Thank you very much!
  2 Comments
xiaojuezi
xiaojuezi on 8 Dec 2021
Hi, the button is a "OK" button, when a user enters something in the edit field, the variable is only set when they press the button. The variables "w","h"......are also used in global scope. So if there are 6 variables, then there are 6 edit fields and 6 OK buttons, and each button should only control an associated edit field and variable.

Sign in to comment.

Accepted Answer

Matt J
Matt J on 8 Dec 2021
Edited: Matt J on 8 Dec 2021
Store the numeric result to the UserData property of the button, instead of to individual variables.
edit(1) = uicontrol('Style','edit');
button(1) = uicontrol('Style','pushbutton');
edit(2)= uicontrol('Style','edit');
button(2) = uicontrol('Style','pushbutton');
input.edits=edit;
input.buttons=button;
[button.Callback]=deal({@setVariable,input})
function setVariable(hObject,eventData,input)
idx=arrayfun(@(a,b) isequal(a,b), hObject, input.buttons);
hObject.UserData = str2double(input.edits(idx).String);
end
  3 Comments
Matt J
Matt J on 8 Dec 2021
You’re welcome. Is the issue solved? If so, please click Accept.

Sign in to comment.

More Answers (0)

Categories

Find more on Migrate GUIDE Apps in Help Center and File Exchange

Products


Release

R2021b

Community Treasure Hunt

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

Start Hunting!

Translated by