Allow modifying operation on Model (e.g. push, insert, remove)

[bryce-happel-walton]

It would be useful to support methods like push, insert, and remove on models directly in .slint code, as well as for slint::Model

(Maybe using += to push.)

Original Description

Slint Vector type or modifyable Model within Slint**

Model has no way of appending or popping from within Slint. It would be good to have a Vector type that can do this.

[ogoffart]

Thanks for reporting this

You're right that it's not possible to add or remove items from a model inside .slint right now.

From rust code, you can do that if you cast to a VecModel:

model.as_any().downcast_ref::<VecModel<MyData>>().unwrap().push(item);

I agree that it might be nice to support methods like push, insert, or remove directly in .slint. I've updated the title and description to reflect that.

[bryce-happel-walton]

I think supporting += means needing to also support that for other append types (numbers). It looks like a new tree_expansion that doesn't match any implementation existing currently.

[ogoffart]

This could be represented by Expression::SelfAssignment
We already special-case += for string, so it could also be done for Model/Array.