Re: [Tile-dev] Strawman Tree widget API

[Joe E. <jen...@fl...>]

Brett Schwarz  wrote:

> [Joe English]
> > I'm not sure how useful user-supplied node IDs are [...]
> 
> One thing I use explicit node names for is so that I
> can identify the node during callbacks (i.e. when
> selected). Think of it as "client data" in the node
> name. I'm not sure if this is the right way to do this
> or not, but I find it comes in handy.

I often do the same thing myself -- often times the data
displayed in the tree comes from some other source that has
its own node identifiers; that's why I chose the BWidget
syntax initially, so the tree widget identifiers match
the source data identifiers.

On the other hand, just about as often the source data *doesn't*
have any notion of a node identifier, so there's an extra burden 
on the programmer to manufacture one.  This could just be a matter
of using "#auto" and letting the Tree widget generate one, 
but still...

> Of course, one
> could just keep a reference to the node id (generated
> from treeview) and client data in a separate
> structure, but I kind of like keeping it together.

That's what you have to do when using the Canvas widget too.

On balance, I think the 2-argument form is preferable to
the 3-argument one.  It's easier to use in the common case,
simplifies the internals, reduces the number of error paths, 
and saves a bit of memory.  I'm strongly leaning towards that 
right now.


> One other thing that I think is missing, is a way to
> find out if a node exists. In BWidgets, it would be:
> 
> $widget exists <nodename>

Would this still be useful if node IDs weren't user-supplied?


--Joe English

  jen...@fl...