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Virtual, Override, and Overload

These three modifiers enable polymorphism in Morph.

virtual​

A virtual method can be overridden by subclasses:

BaseClass class {
    virtual Negate method(a as int) as int {
        return 0 - a;
    }
}

override​

Marks a method as replacing a virtual or abstract method from a parent class:

DerivedClass class inherits BaseClass {
    override Negate method(a as int) as int {
        return -1 * a;
    }
}

overload​

Creates multiple methods with the same name but different parameter signatures:

Calculator class {
    overload Add method(a as int, b as int) as int {
        return a + b;
    }

    overload Add method(a as float, b as float) as float {
        return a + b;
    }
}

Real Example​

From VirtualOverrideOverload.mx:

VirtualOverrideOverload class {
    overload Add method(a as int, b as int) as int {
        return a + b;
    }

    virtual Negate method(a as int) as int {
        return 0 - a;
    }

    override Normalize method(a as int) as int {
        return a;
    }
}

Summary​

ModifierPurpose
virtualMethod can be overridden by subclasses
overrideReplaces a virtual/abstract method
overloadSame name, different parameter types

Next Steps​