Observable doesn't support optional ObservedType

[reuvenlevitsky]

Hey, right now this library has Observable which might support on theory observing optional types. The problem is that when the value is being set, you have this check:

    public var value: ObservedType? {
        didSet {
            if let value = value {
                notifyObservers(value)
            }
        }
    }

That doesn't allow the observing instance to react to the "cleanup" of this model. For example if ObservedType = UIImage, and I want to clean up the image from the UIImageView:

viewModel.thumbnailImage.bind { [weak self] _ , image in
            self?.imageView.image = image
        }

This code will not be invoked for a nil value.

Do you have any plans to support setting nil value to Observable?

[manishkkatoch]

Yes, as of now, it doesn't support the notion of null(nil) as a valid value. There needs to be an explicit way of un-setting the value and notify observers. which would also put the onus on observers to be vary of fact that the value recieved can be nil. I still need to figure out if this should be part of the default behavior and if yes, should it be a strong abstraction (Optional value?)