Modify behavior of struct

ModifyBehavior.swift

struct ModifyBehavior {
    var value: Int
    
    static var operation1: (inout ModifyBehavior) -> Int = { instance in
        instance._operationToUse = operation2
        return instance.value
    }
    
    static var operation2: (inout ModifyBehavior) -> Int = { instance in
        instance.value = 0;
        return 0
    }
    
    var _operationToUse: (inout ModifyBehavior) -> Int = operation1
    
    mutating func operation() -> Int {
        return _operationToUse(&self)
    }
    
    init(value: Int) {
        self.value = value
    }
}

var mod = ModifyBehavior(value: 10)

mod.operation() // 10
mod.operation() // 0
mod.operation() // 0