stevenbrix/DependencyPropertyPrototype

Dependency Property Prototype

This project contains a prototype to show how we can model DependencyProperites after Published properties.

Furthermore, we can also specially generate them in a manner which enforces type safety when using Styles/Setters.

See the code in Sources dir for the API and explanation.

See the Tests for use cases

Usage

Change notifications

let myDO = MyDO()
myDO.myProperty = "hello"
myDO.$myProperty.sink {
    XCTAssertEqual($0, "hello")
    XCTAssertEqual($1, "world")
}

myDO.myProperty = "world"

Style type enforcements

let style = Style(targetType: MyDO.self) {
    Setter(.myProperty, "hi")
    Setter(.myIntProperty, 2)             
}

Open Questions

The Style class has a type-erased base class StyleBase which is what the API would expose, however this type wouldn't be constructible.

In theory, someone could still apply an incorrect Style to a framework element. For example, something like this is allowed:

let obj = MyDO()
obj.Style = Style(targetType.MyOtherDO) { ... }

The runtime will fail when you do this, but it would be nice to have compile-time validation. Is there a way to validate this?