Class Objects

• Syntax:

  OBJ obj_name "description": [class_name] := {: value <- [data] :};
  

  "obj_name" is the name of the object
  "description" is a string expression
  "class_name" is the class
  "data" is the value assigned to the object; the syntax depends on the class of the object.

• Description:

  A class object is an instance of a class. An object binds the different parts of a class structure to concrete values.

  Example:

  TYPE PhysicalQuantityType  "The type of any physical quantity" =
  RECORD
  {
    Quantity : QuantityType;
    Unit : UnitType;
    Value : Real;
  };
  
  CLASS Time "A class for time"
  SPECIALISES PhysicalQuantityType :=
  {:
    Quantity <- "Time";
    Unit     <- "d";
  :};
  
  OBJ TimeObject "Time object": Time :=
  {:
    Value <- 12458;
  :}