app.as_weak().upgrade().unwrap() vs app.clone_strong()

[aurexav]

I've noticed the first usage everywhere, but why don't we use the second one instead?

[ultimaweapon]

The latter will cause the window to contains a strong reference to itself, which prevent its reference count to reach zero. This will cause a resource to leak.

[aurexav]

Thanks, but could you elaborate more? I thought that when the strong_ref_var goes out of scope, it will also be recycled. How does the resource leak occur?

[ultimaweapon]

I guessed your code is passing a cloned app into it own callback handler. If you pass the one that created with as_weak the app will only have one strong reference so it will be free when its goes out of scope. But if you pass the one that created with clone_strong it will have two strong references.