Weird behavior of new figures in MATLAB - oop

Question

I have created a class-managed GUI in which the following methods are defined
function h = make_figure(this)
h = figure('CloseRequestFcn',#this.close_figure);
this.openFigures(end+1) = h;
end
function close_figure(this, src, event)
this.openFigures(this.openFigures == src) = [];
delete(src);
end
Throughout the life of the GUI maney figures are created and closed with the aid of the methods above. Now the weird part...
If I double click a figure file eg (myfigure.fig) in MATLAB's "Current Folder" window and then try to close it (while the GUI is still alive) then the close_figure method of the GUI's class runs although it wasn't created with h = figure('CloseRequestFcn',#this.close_figure); of make_figure method!!! This is the first weird part. The second weird part is that, although an unintented part of code is executed, it shouldn't create problems because the command this.openFigures(this.openFigures == src) = []; actually leaves this.openFigures unchanged and practically all that close_figure does is to delete(src) which is desirable. Despite the above, my program behaves... weird after the above happens.
I have noticed that if I hit figure in the command window and then close it, everything is OK, the close_figure method is not executed. The problem reveals itself only when opening a .fig file created by the GUI's class.
Any ideas?

Answer 1

I just tried the scenario you described, and I am not seeing any weird behavior; create instance of the class, use it to make a figure, then open a FIG file from the "Current Folder" file browser, and close it..
Here is the class definition I used:
classdef MyFigureClass < handle
properties
openFigures = [];
end
methods
function h = make_figure(obj)
h = figure('CloseRequestFcn',#(src,evt) close_figure(obj,src,evt));
obj.openFigures(end+1) = h;
end
function close_figure(obj, src, evt)
obj.openFigures(obj.openFigures == src) = [];
delete(src);
end
end
end
(Tested in R2012a on Windows XP 32-bit.)
EDIT
Ok I think I know what the problem is. Here are the step to reproduce. First add the following method to the class above:
function save_figure(obj, idx)
saveas(obj.openFigures(idx), sprintf('fig%02d.fig',idx))
end
Now using our class wrapper, lets create a figure, and save it to FIG file:
f = MyFigureClass();
f.make_figure()
f.save_figure(1) %# creates fig01.fig
Next clear your workspace clear all, and move the class definition file MyFigureClass.m to some other folder (something not on the path). Now try to load the saved figure hgload fig01.fig, and it will throw the error:
Warning: Cannot load an object of class 'MyFigureClass':
Its class cannot be found.
> In C:\Program Files\MATLAB\R2012a\toolbox\matlab\graphics\hgload.p>localLoadFile at 167
In C:\Program Files\MATLAB\R2012a\toolbox\matlab\graphics\hgload.p>hgload at 59
In openfig at 72
In open at 159
In uiopen at 196
You will have to issue the following command to forcefully close it:
close all force
EDIT2
One solution (as mentioned in the comments), is to reset the figure close callback function just before saving it. Here is how I modified the save_figure function above:
function save_figure(obj, idx)
%# backup callback function
fcn = get(obj.openFigures(idx),'CloseRequestFcn');
%# set default callback function
set(obj.openFigures(idx),'CloseRequestFcn','closereq')
%# save figure
saveas(obj.openFigures(idx), sprintf('fig%02d.fig',idx))
%# restore callback function
set(obj.openFigures(idx),'CloseRequestFcn',fcn)
end

Answer 2

I just wanted to point out that there is a related issue here that others may face. You should NOT open your GUI by double clicking the gui.fig file. This is not the desired behavior because your opening function will never be called. Should you have code in there as many of us do it will not execute, another side effect is that the handles variable will also not be set properly.
What you SHOULD do is either open it in GUIDE first then click run, or run the gui.m file directly. That will yield the desired results and the gui will function as intended.