[Unity] Bug: Fields with internal type exposed via explicit interface is always undefined

[David]

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Puer Version

2.0.5

Unity Version

2023.2

Platform

All

Error Message

No response

Bug reproduce

This pattern is used by Unity's UI Toolkit. VisualElement.style and VisualElement.resolvedStyle are both backed by internal types InlineStyleAccess and ResolvedStyleAccess. When accessing any related fields (i.e. VisualElement.style.width or VisualElement.width) from JS, it'll always return undefined.

Here's a minimal test case.

// C#
namespace MyNamespace {
    public class FooVE {
        public IFoo foo;

        public FooVE() {
            foo = new FooAccess();
        }
    }

    public interface IFoo {
        float width { get; }
    }

    internal class FooAccess : IFoo {
        public float width => 1.23f;
    }
}

// JS
var fooVE = new CS.MyNamespace.FooVE()
console.log(fooVE) // MyNamespace.FooVE
console.log(fooVE.width) // undefined

[chexiongsheng]

your test code is wrong.
The correct version is:

var fooVE = new CS.MyNamespace.FooVE()
console.log(fooVE) // MyNamespace.FooVE
console.log(fooVE.foo.width)

You are not using TypeScript? If you using TypeScript, compiler will point out your mistake.

[David]

Ah yes sorry, I did the minimal test case too fast (and didn't use TS). Let's fix that.

// CS
public class FooVE {
    public IFoo foo;

    public FooVE() {
        foo = new FooAccess();
    }

    public float GetWidth() {
        return foo.width;
    }
}

public interface IFoo {
    float width { get; }
}

internal class FooAccess : IFoo {
    float IFoo.width => 125f; // Note the explicit interface `IFoo.`
}

public class FooTest { // Testing access from another class
    public static void Test() {
        var fooVE = new FooVE();
        Debug.Log(fooVE.foo.width);
    }
}

// JS
var fooVE = new CS.FooVE()
console.log(fooVE) // FooVE
console.log(fooVE.foo.width) // undefined
console.log(fooVE.GetWidth()) // 125
CS.FooTest.Test() // 125

[David]

Ty for the quick fix!🎉