control. I use it, for example, to get the values in a property page when I
am moving to another page if I want to share the data through the parent.
validation stuff is not a problem of UpdateData() so far as I can tell. It's
hander. That will cause it to continually call your handler. You just have
In article news:<eivzQB5xGHA.4972@TK2MSFTNGP03.phx.gbl>, Tom Serface
wrote:
I know there is some disagreement as to whether or not to use
UpdateData(),
but I find if you use it according to design it works quite well.
I agree ... but I would say that the design does not intend UpdateData to
be
called explicitly from user code. It certainly works well if you don't!
Unless you have a whole lot of controls and/or do the updates too often
the cost in time is not to daunting and it's very easy to work within
the framework.
But ... why would you want to call UpdateData any time before the user
dismisses the dialog with "OK". At that point the framework calls
UpdateData
for you, so you don't ever need to call it yourself.
[Exception: I do call UpdateData in the implementation of a dialog's
"Apply"
button.]
I'm talking about modal dialogs, here, of course. I don't think DDX works
very well in cases where you'd want to use a modeless dialog.
... it was much easier to use it when we had ClassWizard.
Absolutely!
You're right that DDX was not designed (at least well) to do the
validation, ...
DDX (well, DDV) was deigned to do validation. There's an implicit design
in
using DDX/DDV that validation is to be deferred until the dialog is
dismissed, and then the value "exchange" (i.e. getting values from
controls
and shoving them into C++ variables) and validation occur together. That's
generally speaking the way that Windows apps do this stuff, and although
Joe
would say that it's better to do validation on the fly (and cite usability
studies to prove it) I think it's better to provide a "user experience"
that's familiar to the user -- we can't change what the rest of Windows
does
but we can be consistent with it.
The DDV mechanism works well if you're prepared to accept deferred
validation, and it's extensible (and there's even class wizard support for
the extensibility ... if you're using VC6).
In the beginning of MFC it was the linkage through DDX/DDV and
UpdateData()
that made it so easy to use. I can see how it could be confusing, but it
has worked well for me in lots of programs over the years.
Agreed ... it works well *unless* you want on-the-fly validation. I
wouldn't
try to use it for that ... but then I wouldn't recommend doing that.
Cheers,
Daniel.