Selectors: recursive mixin check?

[kubukoz]

Hi! I was wondering if there's a way to write a selector that checks if the given shape has a mixin... but checking recursively.

For example, consider this model:

$version: "2"

namespace demo

@mixin
structure MyMixin {}

@hasMyMixin
@mixin
structure Direct with [MyMixin] {}

// structure Indirect with [Direct] {}

@trait(selector: ":test(-[mixin]-> structure [id = 'demo#MyMixin'])")
structure hasMyMixin {}

In its current state, it's valid. However, if you uncomment Indirect it no longer matches (it inherits the hasMyMixin trait, but that fails to validate on Indirect due to the mixin being transitive).

Would it make sense to expand the mixin relationship, or provide a recursive variant of -[...]->? Perhaps a "forward directed recursive neighbor" syntax, like -[...]~>?

Is there a better, existing way to do what I'm looking for? (without resorting to Java)

[mtdowling]

Maybe we could add a synthetic “transitiveMixin” relationship available to selectors which includes direct and transitive mixins. Or maybe a :hasMixin(a, c, c) function that returns true if all mixins are present on a shape. I like the relationship but we’d need to see how disruptive it is vs a function.