[Zope] Modal behaviour wanted!

[Luca Manini]

Hi, 

I'looking for a standard and flexible way (a Zope idiom) to do in Zope
what's really easy to do in a normal GUI (no web) for a very common
problem.

Suppose I have an index_html that lists some items.
Each item has a link that allows to edit it. 
After edit I want to come back to the list [see 1]. 

The edit process will probably require: 

1) a form (edit_html) to be displayed (to collect data),
2) a PythonScript (edit_script) to do the actual job, 
3) a form (edit_ack) to be shown (to say OK or ERROR)

If everything goes fine I will (probably) like to go back to
index_html, if there is an error I will like to (at least once) go
back to edit_html.

Of course I don't want the edit_html to know (hard-coded) that its
"backlink" is index_html (it will not always be the case). 

I can accept edit_script and edit_ack to know who call them (it will
be probably be edit_html), but also in edit_ack it would be nice to
have a way to go back to the original caller (with a Cancel button).



When doing everything from a Python Product, things are somewhat
easier because you are always in the context of the edited/added
object and you can mantain some "editing state" and return the
appropriate form; but how to do it just with DTML Methods and Python
Scripts?

	Any hint?
	TIA, Luca.

PS: Almost all the "small" Zope examples I've seen do not help a lot
    in this regard because quite often they use the FORM action and a
    single button (too simple for real cases), or they use a single
    kitchen-sink DTML with <dtml-if> and some trick to hold state
    (does not scale well).

[1] Note: that's the same like adding an Folder to a Folder, but:

1) after adding the folder, you're sent back to the "right" place
   because everything is done by manage_addFolder that is called in
   the context of the contaning Folder and has the "backlink"
   (self.manage_main) hard-coded in its python code.

   So this is not a general "solution".

2) If everything goes fine you do not get any confirmation (ok you get
   the list and you see the new Folder),

3) If there is an error (ex: duplicated id) you are left with a Zope
   traceback with NO LINK to the original place.