[cells-devel] Inheritance from model, not model-object?

[Mikko Ahonen]

On Wed, Jul 9, 2008 at 1:41 AM, Kenny Tilton <kennytilton at optonline.net>
wrote:

Thanks for the quick reply,

If you saw something in model absolutely necessary for Cells to work, I
> goofed. :)
>

My question was based on error message that indicated that model-object was
not exported (or something) when I was trying to inherit from model-object.

I looked into doc/*.lisp, test-cells/* and also cello, and only found
references to model, not model-object. I figured that perhaps model-object
was some left-over from previous versions, or something.

This is what I got:

"Error during finalization of class #<STANDARD-CLASS X 2173E1B3>: Cannot
compute the class precedence list of #<STANDARD-CLASS X 2173E1B3> because
the following class is not finalized #<FORWARD-REFERENCED-CLASS MODEL-OBJECT
223FBB43>"

(this is LispWorks 5.1 on OS X if it makes any difference, and extending a
GUI component)

Works fine with model, though.

Cool. Philip Eby also talks about callback madness as motivating his Cells
> clone, Trellis (a Python project). I never thought about it as a callback
> thing, but it seems to be a recurring theme. :)
>

Not that I would know much about GUIs, but perhaps it depends on the model
used in the GUI library. I am now experimenting with LispWorks CAPI.

For example this screen become a hassle immediately with callbacks, even if
it is quite simple in principle:

User is editing two-level hierarchical data. Thus, parent objects have
children. This view shows single parent. The form on the right is used to
edit a single child. On the left I have preview of each child for this
parent. The child previews are clickable, and select the object for editing.
When I edit the data, the underlying model should obviously change. So
should the preview, if corresponding fields change, as well as the title and
some other parts of the view as well.

Best regards,

Mikko Ahonen
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