How to pass handle without using nested functions?

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Zoltán Csáti
Zoltán Csáti 2013-6-23
I want to make a simple GUI programatically. Here is what I have done so far.
function main
% Initialize figure and axes
screenSize = get(0,'ScreenSize');
f = figure;
set(f, 'Visible','on', 'Resize','off', 'MenuBar', 'none', ...
'NumberTitle','off', 'Name','main', 'Units', 'pixels', ...
'Position',[1 1 0.6*screenSize(3) 0.6*screenSize(4)]);
movegui(f,'center');
a = axes;
set(a, 'Parent',f, 'Units','normalized', 'Position',[0.3 0.1 0.6 0.8]);
% Initialize uicontrols
pushButton = uicontrol('Style','pushbutton', 'String','Example', ...
'Units','normalized', 'Position',[0.1 0.1 0.1 0.1], ...
'Callback',@whenPushed);
% Initialize uimenus
fileMenu = uimenu('Label','File');
fileMenu_Save = uimenu('Parent',fileMenu, 'Label','Save', ...
'Callback',@saveContent);
fileMenu_Exit = uimenu('Parent',fileMenu, 'Label','Exit', ...
'Callback','close(''all'')');
end
function saveContent(fileMenu_Save, EventData)
[file,path] = uiputfile('animinit.m','Save file name');
end
function whenPushed(pushButton, EventData)
disp(pi);
end
When I click on Exit, the figure closes as I intended. But if there are several figures and I only want to close figure f, I must write close( f ) which MATLAB does not recognize. I can solve it by making a function instead of a string like this:
function main
...
fileMenu_Exit = uimenu('Parent',fileMenu, 'Label','Exit', ...
'Callback',@close_Callback);
...
function close_Callback(fileMenu_Exit, EvantData)
close(f);
end
end
But I would like to do this without nested functions. How can I solve then?

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per isakson
per isakson 2013-6-23
编辑：per isakson 2013-6-23
Callbacks are invoked from the base workspace. Thus, the arguments passed when calling the callback-function must be in the base workspace. The figure handle, f, is in the main-function-workspace.
Your figure is the current figure when you click the file-menu. Thus, it is safe to use the function, gcf.
Try close(gcf) as in
fileMenu_Exit = uimenu('Parent',fileMenu, 'Label','Exit', 'Callback','close(gcf)');
What's wrong with nested the function? I cannot think of a better way to pass the handle, f. You can use userdata or appdata. GUIDE uses guidata which is a wrapper of appdata.It is possible to make the handle, f, available in the base workspace: assignin( 'base', ... )
Give the figure a good name, my_good_name, and use close( 'my_good_name' ) in the callback.
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per isakson
per isakson 2013-6-23
编辑：per isakson 2013-6-23
A few comments:
  • Design is little discussed in the Matlab fora
  • I think close( 'my_good_name' ) is a good way to close the figure. It is simple, robust and self-documented.
  • There is a "design pattern" sometimes called redblue, which is based on nested functions. See: GUI Examples using Nested Functions. I found that useful and it was my first choice for several years. (Now, I wrap the handle graphic objects in user classes - however that is often over-kill.) One nice thing with nested functions is that you can create function handles and pass these around to other functions like any other variable.
  • Did you check 41 Complete GUI Examples by Matt Fig.
  • avoid assignin. It's in the same category as eval, global, etc. And it a) litters the base workspace, b) makes the handle visible to the user, ... .
Zoltán Csáti
Zoltán Csáti 2013-6-23
Thanks for the comments. I am currently watching Matt Fig's method and he also uses nested functions. This seems to be a proper way.

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