Refactoring for ModelProtocol protocol

[hachinobu]

Hi, @malcommac

Thank you for providing a nice library.

Please tell me about the implementation of ModelProtocol.

If the object conforms to the Equatable protocol, i can use the default implementation of Extension so i do not need to write isEqual method.

Likewise, if the object conforms to the Hashable protocol, i do not want to write the identifier property.

Is there a problem with the code below?

extension ModelProtocol where Self: Hashable {
	
    public var identifier: Int {
        return self.hashValue
    }
    
    //remove code
//    public var hashValue: Int {
//        return self.identifier.hashValue
//    }
	
}

It seems that compatibility is good.

Synthesizing Equatable and Hashable conformance

I think that implementation will be easier.

best regards.

[malcommac]

Hi, you are correct, ModelProtocol is pretty weird yet.
My initial concern is to force the user to adopt this protocol in order to be conform to Hashable protocol, used internally to perform diffing between two data reloads.
In fact, actually is a mix of bad practices.
I've tried to refactor it by removing both isEqual function and identifier variable.
ModelProtocol right now must implement only a variable, hashValue (the same you need to be Hashable conform, even this is a just a repetion). What do think about it?

public protocol ModelProtocol {
	var hashValue: Int { get }
}

Inside the diff functions are models are therefore casted to AnyHashable, if it fails a debugPrint is printed to the console.

[malcommac]

I've changed partially changed the approach to make it much cleaner.

Each model of the cell must be conform to the ModelProtocol protocol.
This protocol require the implementation of a single property called modelID (an Int) which is used to uniquely identify an object for DeepDiff.

A default implementation of this property is provided via ObjectIdentifier for class-based objects (AnyObject).
Instead an explicit implementation must be provided for value based objects (for example structs).