Universe.swift

class A {
    /// A `Bool` indicating if we have the answer to the universe.
    private(set) var hasAnswer = false
    /// The instance of `BType` we are using to check if we have the answer.
    private let b: BType
    
    init(b: BType) {
        self.b = b
    }

    /// Checks if we have the answer to the universe and updates the `hasAnswer` property.
    func checkAnswer() {
        hasAnswer = b.validateAnswer()
    }
}

class B: BType {
    /// The `CType` used to get the number.
    private let c: CType
    
    init(c: CType) {
        self.c = c
    }
    
    /// Validates if `c` has the answer.
    func validateAnswer() -> Bool {
        c.number == 42
    }
}