Crash when using .debug

[technologybrother]

I'm sure it's an obvious mistake on my part and I had no problems before, but I wasn't able to identify the offending code that causes .debug() to result in following error:

As soon as I remove .debug() everything works like charm.

[mbrandonw]

Hi @ndistqt, thanks for the report! This is a bummer, but we seen some weird behavior in Swift's mirror before, especially when dealing with types from some of Apple's frameworks.

I see the value here is an AXUIElement. Is that being held in your state or your action?

[mbrandonw]

I may need to see more of your state/actions that is causing this because locally it seems that debugOutput seems to run fine with an AXUIElement, just try out this test:

  func testAXUIElement() {
    let element = AXUIElementCreateApplication(1)

    XCTAssertEqual(
      debugOutput(element),
      """
      """
    )
  }

[technologybrother]

The debugOut function is not found although I have the ComposableArchitecture imported.

[mbrandonw]

Are you able to reproduce this problem in some code that I can run locally?

Also what is UIElement? It doesn't look like it's an Apple type.

[technologybrother]

"Are you able to reproduce this problem in some code that I can run locally?"

• I'll try to find out and let you know.

UIElement is from the library AXSwift, which you can find here on github, it's just a wrapper around Apple's accessibility API for better ergonomics.

[stephencelis]

Hey @ndistqt we took a quick look at AXSwift and it looks like the UIElement custom string convertible conformance does some pretty side-effecty things, like accessing a process ID and calling out to NSRunningApplication:

https://github.com/tmandry/AXSwift/blob/b4db10b2c28583f5c51033166be60a572ff39dcb/Sources/UIElement.swift#L609

In general we think that state needs to consist of simple value types, and as soon as you introduce classes and objects you expose yourself to a lot of undefined behavior that will be difficult to test. If you need parts of these classes in your state we recommend defining structs that hold just the value-based data you care about. It can sometimes be a bit of a pain to add this boilerplate, but it will give you peace of mind that your system is working in a predictable manner.