[cells-devel] Re: Celtk contrib: ttk::treeview

[Kenny Tilton]

Madhu wrote:
> * Kenny Tilton <48DFA037.3030705 at optonline.net> :
> Wrote on Sun, 28 Sep 2008 11:18:15 -0400:
> |> The issue was that I could not figure out how to limit expansions down
> |> the tree using a kids rule at make-instance time.
> |
> | That was what I was trying to suggest with the above excerpt, but I
> | was too terse: just have the kids rule first check another cell, the
> | openp slot. When that goes to t the kids will be generated, when it
> | goes to nil they can go away. If you think you need to avoid
> | recreating the clos instances you are probably wrong, but you can just
> | make the container collapsed when not openp (and play any number of
> | tricks to avoid the rule rerunning when openp goes to nil and tossing
> | all the kids.
> 
> openp is a slot on treeview-item that controls the ".pathname item -open
> node" tcl command. I'm using `openedp' for a new variable.
> 
> | ie, This is a very common requirement solved without SETF. But I
> | commend your creativity in finding a solution, and the extensive work
> | you did wiring in treeview. You are a quick study!
> |
> |
> |> The general idea was
> |> directories should be expanded only when needed.  [Further I was using
> |> `expandedp' to ensure that directories got expanded only once, even if
> |> they were opened multiple times by on-open events].  I couldn't combine
> |> these requirements with the desired initial state.
> |
> | No, you forgot to ask me how. But I understand, I usually charge ahead
> | on my own too and Just Get It Working.
> 
> You know what?  Youre right.   I'm appending the code to this message,
> it is a bit simpler without those :after methods on make-tk-instance.
> 
> There is still a question -- of triggering a (setf (^openp) t) in a
> dirtree-node kids rule.
> 
> |> Besides, this was supposed to demo the idea that the tree represented in
> |> the family's hierarchical model is directly displayed by the widget. So
> |> manipulating the model (adding kids, sorting the kids) should reflect in
> |> the displayed tree.
> |
> | ? How does this mandate abandonment of the declarative paradigm?
> 
> The declarative paradigm is already there, to be chosen and used.  All
> that is being done is support is also added for a traditional
> container-contains hierarchy, so one can reach for it JUST IN CASE one
> needs it.
> --
> Madhu
> 
> PS: Here is the code, in full declarative glory :)

<snip>

OK, /now/ you can go on your long vacation.

:)

kt