moduleceylon.language1.0.0
Source Code
ceylon.language
classObject
OverviewPackageAttributesInitializerMethods
Type Hierarchy:
Direct Known Subclasses: Array<Element>, Basic, Character, Entry<Key,Item>, Float, Integer, Range<Element>, Singleton<Element>, String, Tuple<Element,First,Rest>, empty, emptyMap, emptySet
All Known Subtypes Hierarchy

The abstract supertype of all types representing definite values. Any two Objects may be compared for value equality using the == and != operators:

true==false
1=="hello world"
"hello"+" "+"world"=="hello world"
Singleton("hello world")=={ "hello world" }

However, since Null is not a subtype of Object, the value null cannot be compared to any other value using ==. Thus, value equality is not defined for optional types. This neatly voids the problem of deciding the value of the expression null==null, which is simply illegal.

By: Gavin
See also: Basic, Null
Initializer
Object()
Attributes
hashSource Code
shared formal Integer hash

The hash value of the value, which allows the value to be an element of a hash-based set or key of a hash-based map. Implementations must respect the constraint that if x==y then x.hash==y.hash.

stringSource Code
shared default String string

A developer-friendly string representing the instance. Concatenates the name of the concrete class of the instance with the hash of the instance. Subclasses are encouraged to refine this implementation to produce a more meaningful representation.

Methods
equalsSource Code
shared formal Boolean equals(Object that)

Determine if two values are equal. Implementations should respect the constraints that:

  • if x===y then x==y (reflexivity),
  • if x==y then y==x (symmetry),
  • if x==y and y==z then x==z (transitivity).

Furthermore it is recommended that implementations ensure that if x==y then x and y have the same concrete class.