KEP001: Instantiate things other than widgets from kv

[matham]

KEP (kv enhancement proposal) 001 instantiate other things than widgets from kv: https://github.com/kivy/kivy/wiki/KEP001:-Instantiate-things-other-than-widgets-from-kv

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[ghost]

Have you considered a 'properties:' or similar at the top level?

<SomeWidgetClass@Widget>:
    properties:
        NumericProperty:
            name: my_numeric
            default: 20
        StringProperty:
            name: my_string
            default: 'default value' # never binds, but can read id.prop values at instantiation
            value: str(root.my_numeric*2) # or some_id.propname; always binds

Seems a bit more consistent with the current canvas: syntax and might be easier/faster to parse (guessing). Maybe add 'animations:' and/or others.

Rgd id/name, my vote is to leave id for widgets; seems confusing to mix them.

[inclement]

Of the given options, I like #5/6 the most, by a long way. I think the others are unnecessarily syntactically inconsistent with the rest of kv.

[matham]

A few things we should be aware when implementing/deciding.

• Not all properties take a value; e.g. AliasProperty doesn't take a value. So syntax shouldn't make us set a value.
• For e.g. ReferenceListProperty and AliasProperty, some of the values are the names of other properties or a function name, these are not available from kv (e.g. x, and y here: https://github.com/kivy/kivy/blob/master/kivy/uix/widget.py#L840). Not sure how we'd deal with them other than by not allowing these properties from kv?

[stale]

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