Classes

Classes have attributes, constructors and functions:

  • Attributes: Every vardecl in classcons and classunit which is a vardecl. Added to the environment of the an object which has the type of the class.
  • Constructors: classcons is a constructor which has vardecls as parameters, where every attribute declared in classcons is assigned with the corresponding argument (the exact same). All other constructors are the class's functions which have the exact same name as the class. Every constructor with the additional _init function must initialize all attributes declared in the class. The function called _init will always be called before the constructor function. Constructor functions mustn't have a return-type. Immutable variables can be assigned once in the constructor. Contructors are added to the parent environment of the class.
  • Functions: Every classunit which is a func, which isn't a constructor.

The name of the class (second expression id in classdecl) must start with an uppercase character with optional leading '_'.

Examples:

class Person
	&_Name : String
	&_age : u8

	func Person(This, Name : String, age : u8)
		._Name = Name
		._age = age
	;

	func getName(This) =
		._name;
	
	func getAge(This) =
		._age;
;

// A bit less code ...
class Person(&_name : String, &_age : u8)
	func getName(This) =
		._name;

	func getAge(This) =
		._age;
;

Implementing traits

Functions declared can be implemented by classes to support polymorphism. traitimpl must contain all functions declared by the mentioned trait after : in traitimplbody. A trait already implemenated in the functions cannot be reimplemented.

Creating an object

An object is created by making function call where the called function is a reference to the class.

Class environment

Accessing the environment of the class:

  • Every function has every direct attribute and function of the class in the parent environment

  • To access the class environment directly the left-unrary operator . must be used

This

This is the keyword which represents the closest parent class environment as type (same as writing the class name).

Functions

The first parameter of every class function must have the same type as the class. This can be achieved with This. If the first parameter doesn't have a variable name (just the type), then the variable this with current class as type is added to the environment of the function body.

Functions are added to the environment of the class semantic and are added to class' instances without the first parameter.