Classes

Zap supports heap-only class types allocated with new.

Defining a class

class Counter {
    priv value: Int;

    fun init(value: Int) {
        self.value = value;
    }

    pub fun inc(step: Int) Int {
        self.value = self.value + step;
        return self.value;
    }
}

Creating instances

var counter: Counter = new Counter(10);

init(...) acts as the initializer. self is available inside instance methods.

Visibility

Visibility modifiers:

• pub
• priv
• prot

Inheritance and dynamic dispatch

Single inheritance is supported:

class Base {
    pub fun value() Int {
        return 1;
    }
}

class Derived : Base {
    pub fun value() Int {
        return 2;
    }
}

Methods dispatch dynamically through the base type.

Another example

class Task {
    prot done: Bool;

    fun init() {
        self.done = false;
    }

    pub fun finish() {
        self.done = true;
    }
}

Lifecycle hooks

Classes can define:

• init(...) for initialization
• deinit() for cleanup on final release

Weak references and ARC details are covered in ARC and weak refs.