open a variable in a function

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Abel Tan
Abel Tan 2019-1-31
评论： Jan 2019-2-1
Hello,
I have a dialog box created within a function. Within the dialog box is a pushbutton with a callback that is planned to create a variable and then opens it in the variable editor, all this while the dialog box is still active. If i close the variable editor and press the same button again, it should open the variable in the variable editor again.
I have tried using openvar() but openvar opens variables from the workspace in scope, which is the 'base' workspace during a callback. The variable is created in the callback and thus openvar() does not work for me.
how can I open the variable created in the callback in the variable editor without the use of evalin or assignin?
Thanks!
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Walter Roberson
Walter Roberson 2019-1-31
编辑：Walter Roberson 2019-1-31
The scope for callbacks is the base workspace only for callbacks specified as character vector or a cell array in which the first element is a character vector .otherwise the scope would be the function that is the callback .
Abel Tan
Abel Tan 2019-1-31
thanks for correcting me on that!

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回答（2 个）

Jan
Jan 2019-1-31
编辑：Jan 2019-1-31
I cannot try it currently. Although the callback is called from the base workspace, the current workspace inside the callback is the callback's one. So you can create the variable there:
function YourCallback(hObject, EventData, handles)
X = rand(2, 2);
openvar('X');
pause(20); % For this demonstration only!!!
end
Does this work? Then the assumption, that the Base workspace is used, is not correct. Is your problem solved then?
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Guillaume
Guillaume 2019-2-1
Possibly a drawnow before calling uiwait may display the variables. However, it's never a good idea to suspend a UI callback in order to allow more UI interaction so it may be that it doesn't work either. I think it's clear that the variable editor is not meant to be used as part of a GUI.
is it alright if I leave it without accepting an answer?
Maybe write your own answer summarising the discussion and accept it. Just so, the question has some sort of closure.
Jan
Jan 2019-2-1
"is it alright if I leave it without accepting an answer?"
Yes, this is okay. It is useful for the forum, if you write your own answer and accept this if you've found a working solution.

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Guillaume
Guillaume 2019-1-31
"the workspace in scope, which is the 'base' workspace during a callback"
Not at all. The workspace in scope is that of the callback, not the base workspace. However, that workspace is very short lived and is destroyed as soon as the callback completes. So any callback variable shown in the variable editor won't be displayed anymore when the callback returns. Instead you'll see The variable xxx does not exist.
I don't think there's a way to use the variable editor in conjunction with a GUI. If there is, it's probably going to involve some ugly hacks. Perhaps your best bet would be to use a uitable instead.
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Abel Tan
Abel Tan 2019-1-31
Hi Guillaume,
thanks for the advice.
unfortunately, uitable doesn't fit too well with what I want to do.
I am able to do it using assignin to assign the variable to the base workspace and then using openvar. However, asssignin is kind of a hack which isn't sometimes too easy to debug and troubleshoot when codes get lengthy because it sort of 'spoofs a variable out of nowhere', and kind of shows that much thought hasn't been put into my code.
as such, I would like to avoid it if possible.

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