Creating Objects

Creating Objects

There are two main ways of creating js-type objects: as anonymous objects, and through constructors such as the new operator.

Creating anonymous objects

  • Anonymous (or 'literal') objects in HFL are created the same way as in javascript.
  • { [<obj-field-def> [, <obj-field-def>]*] }
    where:
    <obj-field-def>
    :=
    <key> : <value>
    • Creates a new anonymous object (or 'object literal') containing the field definitions, if any.
    • The <key> values must be unquoted literals that are valid as property names.
    • The <value> values can be any valid expression, such as a constant, an expression, or a function definition.
    • EXAMPLES:

    • var person = {
        name:       'Joe Blow',
        age:        45,
        occupation: 'Plumber'
        };
        
      // Prints "Joe Blow is 45 years old and is a Plumber"
      print(person.name+" is "+person.age+" years old and is a "+person.occupation);

      var place = {};
      place.country = 'France';
      place.city = 'Paris';

      // Prints "Paris is in France"
      print(place.city+" is in "+place.country);

Creating objects using the 'new' operator

  • Objects in HFL are created the same way as in javascript.
  • new <constructor> [([<arguments>])]
    where:
    <constructor>
    :=
    Function that initializes the object
    • Creates a new object of the type defined by the <constructor> function.
    • EXAMPLES:

    • // Create a new generic object
      var myobj = new Object();

      // Constructor function for object 'Pet'
      function Pet(type, name) {
        this.type = type;
        this.name = name;
        }
        
      // Create three 'Pet' objects
      pet1 = new Pet('Dog', 'Fido');
      pet2 = new Pet('Donkey', 'Hodey');
      pet3 = new Pet('Kitten', 'Kaboodle');

      // Prints "My first pet is a Dog named 'Fido'"
      print("My first pet is a "+pet1.type+" named '"+pet1.name+"'");

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