Object Interfaces

• Duck Typing
• Meta-Method Checks
• Interfaces

Duck Typing 

If it looks like a duck, and quacks like a duck, we have at least to consider the possibility that we have a small aquatic bird of the family anatidae on our hands.

— Douglas Adams

Like PHP, THT is a dynamic language, so an object’s class or type does not need to be checked before you can call its methods.

This technique is called Duck Typing, because if an object “walks like a duck, and talks like a duck... then it’s a duck.”

This allows you to use objects from different classes in the same way, as long as they define the same methods.

Example

In this example, two classes have a talk method.

class Cat {
    fn talk: print('>Meow<')
}

class Coder {
    fn talk: print('1001010011101')
}

// Another File
//---------------------------------------

fn greet($creature) {
    // Any object that has a 'talk' method will work.
    $creature.talk()
}

$kitty = Cat()
greet($kitty)  //= '>Meow<'

$kody = Coder()
greet($kody)  //= '1001010011101'

Meta-Method Checks 

You can also use meta-methods like zHasMethod to explicitly check if an object has the given method.

fn greet($creature) {
    if $creature.zHasMethod('talk') {
        $creature.talk()
    }
}

Interfaces