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From "David Geary" <>
Subject Re: [dialog] Get rid of subdialogs
Date Thu, 24 Aug 2006 03:46:08 GMT
I agree that it's often useful for a subdialog to access data contained in a
parent dialog, or as SHALE-153 points out, vice-versa. Use cases where
subdialogs are entirely self-contained would certainly seem to be in the

OTOH, I don't think this necessarily warrants a change to subdialog design
because dialogs  have the mechanisms to deal with this. The starting state
for a subdialog can be an action state, and that method can set up the reference before entering the first view state.

What the reference points to, and whether that object has access
to the data object of the enclosing dialog (or vice-versa) seems like more
of OO design issue that's separate from the dialogs themselves.


2006/8/23, Sean Schofield <>:
> I'm not quite convinced that <subdialog> is very useful as
> implemented.  I see the usefulness in stringing existing dialogs
> together but certain byproducts of subdialog are undesirable.  For
> instance, SHALE-153 which complains about how you can't easily access
> state information between a "parent" and "child" dialog.
> I've discussed this with Craig before and IIRC he doesn't agree with
> me on this but I can't see how having subdialogs as "black boxes" is
> very useful.  Maybe there are some use cases out there but it would
> seem to me that its much more common that you would want to share
> state across two dialogs.
> Here's a hypothetical example:  Suppose you have a e-commerce site
> where you sell both physical products as well as downloadable
> software.  You have the following "dialogs":
> shopping cart
> shipping
> payment
> download link
> Each of these "dialogs" represents a series of actions and views.  For
> the physical goods you might want to compose a "physical goods" dialog
> as follows:
> shopping cart -> shipping -> payment
> For the downloadable software you might want to compose a dialog that
> uses the same shopping cart and payment dialogs as in the physical
> goods case:
> shopping cart -> payment -> download link
> If you compose these using <subdialog> you immediately run into
> problems.  Your payment dialog has no access to any of the state
> generated by the shopping cart phase of the dialog.  As a developer I
> don't want shopping cart and payment to be black boxes, I want them to
> work seamlessly together.  I also don't want to configure the shopping
> cart and payment stuff twice in order to avoid this.
> I think the ability to plug dialogs into one another is really cool
> but in the past I have found myself doing various hacks and
> workarounds to get at the state information further down the stack.
> Of course we could make it optional to create a new state for the
> subdialog but there are other reasons not to bother with this.  I have
> implemented my own prev, next, ok button scheme on top of shale
> dialogs and subdialogs significantly complicate this.
> Sean

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