Classes

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Classes
A class is a declaration of a constructor of objects with a specific type. Each object has zero or more attributes (instance variables) with zero or more behaviours (methods), that are defined inside a specific class or inherited from super-classes.
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class Person (name, age, address) {
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    method position {
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        # GPS.locate(self.address)
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    }
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​
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    method increment_age(amount=1) {
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         self.age += amount
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    }
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}
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​
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var obj = Person(
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       name: "Foo",
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        age: 50,
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    address: "St. Bar"
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)
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​
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say obj.age                # prints: 50
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say obj.name               # prints: "Foo"
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say obj.address            # prints: "St. Bar"
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​
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obj.name = "Baz"           # changes name to "Baz"
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say obj.name               # prints: "Baz"
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​
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obj.increment_age          # increments age by 1
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say obj.age                # prints: 51
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Class attributes
The attributes of a class can be either specified as parameters, or declared with the has keyword.
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class Example(a, b) {
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   has c = 3
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   has d = a+c
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}
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​
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var obj = Example(1, 2)
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​
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say obj.a   #=> 1
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say obj.b   #=> 2
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say obj.c   #=> 3
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say obj.d   #=> 4
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Class initialization
Extra object-initialization setup can be done by defining a method named init, which will be called automatically called whenever a new instance-object is created.
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class Example (a, b) {
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​
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   has r = 0
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​
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   method init {      # called automatically
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      r = a+b
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   }
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​
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   method foo {
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      r
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   }
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}
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​
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var obj = Example(3, 4)
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say obj.foo              #=> 7
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Class variables
The syntax ClassName!var_name can be used for defining, accessing or modifying a class variable.
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class Example {
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​
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    Example!hidden = 'secret'    # global class variable
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​
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    method concat (str) {
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        str + ' ' + Example!hidden
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    }
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}
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​
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var x = Example()
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var y = Example()
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​
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say x.concat('foo')   #=> 'foo secret'
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say y.concat('bar')   #=> 'bar secret'
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​
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Example!hidden = 'public'  # changing the class variable
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​
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say x.concat('foo')   #=> 'foo public'
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say y.concat('bar')   #=> 'bar public'
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The modification of a class variable can be localized by prefixing the declaration with the local keyword:
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local Example!hidden = 'local value'
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Class inheritance (experimental)
Inheritance of behaviors and attributes, by a given class, is declared with the < operator, followed by the name of the class from which the current class inherits:
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class Animal(String name, Number age)  {
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    method speak { "..." }
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}
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​
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class Dog(String color) < Animal {
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    method speak { "woof" }
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    method ageHumanYears { self.age * 7 }
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}
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​
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class Cat < Animal {
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    method speak { "meow" }
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}
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​
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var dog = Dog(name: "Sparky", age: 6, color: "white")
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var cat = Cat(name: "Mitten", age: 3)
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​
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say dog.speak          #=> woof
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say cat.speak          #=> meow
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say cat.age            #=> 3
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say dog.ageHumanYears  #=> 42
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say dog.color          #=> white
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Multiple inheritance is declared with the << operator, followed by two or more class names, separated by commas:
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class Camera { }
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class MobilePhone { }
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class CameraPhone << Camera, MobilePhone { }
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Modules
Types
Last modified 1yr ago
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Contents
Class attributes
Class initialization
Class variables
Class inheritance (experimental)