Classes

Search…
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.
class Person (name, age, address) {
    method position {
        # GPS.locate(self.address)
    }
​
    method increment_age(amount=1) {
         self.age += amount
    }
}
​
var obj = Person(
       name: "Foo",
        age: 50,
    address: "St. Bar"
)
​
say obj.age                # prints: 50
say obj.name               # prints: "Foo"
say obj.address            # prints: "St. Bar"
​
obj.name = "Baz"           # changes name to "Baz"
say obj.name               # prints: "Baz"
​
obj.increment_age          # increments age by 1
say obj.age                # prints: 51
Class attributes
The attributes of a class can be either specified as parameters, or declared with the has keyword.
class Example(a, b) {
   has c = 3
   has d = a+c
}
​
var obj = Example(1, 2)
​
say obj.a   #=> 1
say obj.b   #=> 2
say obj.c   #=> 3
say obj.d   #=> 4
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.
class Example (a, b) {
​
   has r = 0
​
   method init {      # called automatically
      r = a+b
   }
​
   method foo {
      r
   }
}
​
var obj = Example(3, 4)
say obj.foo              #=> 7
Class variables
The syntax ClassName!var_name can be used for defining, accessing or modifying a class variable.
class Example {
​
    Example!hidden = 'secret'    # global class variable
​
    method concat (str) {
        str + ' ' + Example!hidden
    }
}
​
var x = Example()
var y = Example()
​
say x.concat('foo')   #=> 'foo secret'
say y.concat('bar')   #=> 'bar secret'
​
Example!hidden = 'public'  # changing the class variable
​
say x.concat('foo')   #=> 'foo public'
say y.concat('bar')   #=> 'bar public'
The modification of a class variable can be localized by prefixing the declaration with the local keyword:
local Example!hidden = 'local value'
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:
class Animal(String name, Number age)  {
    method speak { "..." }
}
​
class Dog(String color) < Animal {
    method speak { "woof" }
    method ageHumanYears { self.age * 7 }
}
​
class Cat < Animal {
    method speak { "meow" }
}
​
var dog = Dog(name: "Sparky", age: 6, color: "white")
var cat = Cat(name: "Mitten", age: 3)
​
say dog.speak          #=> woof
say cat.speak          #=> meow
say cat.age            #=> 3
say dog.ageHumanYears  #=> 42
say dog.color          #=> white
Multiple inheritance is declared with the << operator, followed by two or more class names, separated by commas:
class Camera { }
class MobilePhone { }
class CameraPhone << Camera, MobilePhone { }
Modules
Types
Last modified 2yr ago
Copy link
Outline
Class attributes
Class initialization
Class variables
Class inheritance (experimental)