Re: custom treemodel?

[Paul Davis <pjdavis engineering uiowa edu>]

Jonathon Jongsma wrote:

> > Why would he need to derive a class? Wouldn't the templated class be 
> > enough?
>
>
> Well, the CustomTreeModel class can implement a lot of the virtual
> functions (i.e. iter_next_vfunc, things like that), but it can't very
> easily implement anything related to values that are stored in the
> container.  For example, say you want a custom treemodel that uses
> std::vector<rgb_t> where rgb_t is defined as
> struct rgb_t
> {
> int r, g, b
> }
>
> Do you want the model to have a single column of rgb_t objects, or do
> you want three columns: an red column, a green column, and a blue
> column?  Unless we want to limit the CustomTreeModel to only ever
> having a single column, I think we need to rely on a more-derived
> class to determine how the columns are defined (i.e. it needs to
> implement get_n_columns_vfunc, etc.).  This certainly makes it more
> complicated, but it also makes it more flexible.  But if you have any
> ideas of how to do it all in one class, I'd certainly be happy to do
> it that way.
I agree with this whole heartedly. If we start making assumptions about 
what gets passed to this class, it starts to lose some of its use.  
Unless theres a very very good cause for doing so I'd recommend making 
any assumptions.

Even though we might be thinking of using this to wrap tree models 
around STL containers, whats to stop someone from passing it a linked 
list of some non-standard format. Or what if we wanted to do something 
even simpler and just pass it an NxM dimensional array?

Looks good so far.  And I sure am glad I'm not the one scratching my 
head about virtual inheritance and GObjects...as much fun as it sounds.

Paul