On Sun, Aug 26, 2012 at 7:42 PM, Art Heimsoth <artst...@artheimsoth.com> wrote:
> What is the proper way to end a program where an error is detected
> with system data in the Init or InitDialog methods?
If you detect an error in the init() method, the best thing to do is
to set initCode to non-zero. Then after you do the .MyDlg~new, check
the initCode.
Many / some of the examples do check the initCode, but with a lot of
my programs I stopped doing that. (I know I'm not setting initCode to
non-zero, and it is almost impossible for an internal error to
happen.) On the other hand, if you know that you might be setting the
initCode, then be sure and check it. Like this:
dlg = .CustomDrawDlg~new('customDrawListview.rc', IDD_CUSTOMDRAW)
if dlg~initCode <> 0 then do
say 'Error initializing dialog. Init code:' dlg~initCode
say 'Aborting'
return 99
end
dlg~execute("SHOWTOP")
return 0
...
::method init
expose textRed textBlack
forward class (super) continue
ret = self~customDraw
if ret <> 0 then do
self~initCode = 17
return self~initCode
end
self~customDrawControl(IDC_LV_CUSTOM, 'ListView', onCustomDraw)
...
In initDialog() on the other hand, the underlying Windows dialog has
already been created, so you want to end with cancel() or ok(). I
usually just do this
::method initDialog
...
do some stuff
if <detected error> then do
-- maybe print an error message
return self~cancel:super
end
> I define some
> fonts in the InitDialog method and then delete them in the Cancel
> method. If on the detected error condition, I invoke the cancel method
> after presenting an error message, I get an invalid argument on the
> DeleteFont() request.
Oh , I see you are already doing it a good way.
What you want to do is over-ride the leaving() method and do your
deleteFont() there. Leaving is especially provided for just this
purpose. The ooDialog framework will invoke that method before the
underlying Windows dialog is destroyed. Something like this:
::method leaving unguarded
expose myFont
self~deleteFont(myFont)
return 0
In fact the program I pulled the first code snippets out of does exactly that.
/** leaving()
*
* This method is invoked automatically by the ooDialog framework when the
* dialog is closed. It should be used to do any needed clean up. Here we
* delete the font we created.
*
* Note that the colors we created are just numbers and do not represent any
* system resource and therefore need no clean up.
*/
::method leaving unguarded
expose checkedFont
self~deleteFont(checkedFont)
return 0
> Also, if I have a method defined to get
> control from a ConnectPosChanged() request, that also gives me
> an error on the dialog requests dealing with changed Edit control
> elements. These items do not give an error if I do not attempt
> to call the Cancel method before the Init or InitDialog methods have
> returned.
Don't call cancel() from init(), use the initCode attribute to signal
an error. In initDialog() it should work fine.
I'd need to see more of your code to understand why you are getting
the error you are talking about. (Actually, after re-reading that
paragraph, I'm not sure I know what you are doing.)
On the face of it, I don't think you should get an error. But, I'd
need to look at your code. It is easily enough fixed, but I don't
want to suggest how until I'm sure I understand what is actually
happening.
Maybe clean up things with my suggestions and if you are still getting
this error, then show more of your code.
--
Mark Miesfeld
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