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@Retention(value=RUNTIME) @Target(value=TYPE) public @interface Immutable
Class annotation used for making a class immutable.
It allows you to write code snippets like this:
@Immutable
final class Customer {
String first, last
int age
Date since
Collection favItems
}
def d = new Date()
def c1 = new Customer(first:'Tom', last:'Jones', age:21, since:d, favItems:['Books', 'Games'])
def c2 = new Customer('Tom', 'Jones', 21, d, ['Books', 'Games'])
assert c1 == c2
A class created in this way has the following characteristics:
ReadOnlyPropertyException
.
equals
, hashCode
and toString
methods are provided based on the property values.
Date
s, Cloneable
s and arrays are defensively copied on the way in (constructor) and out (getters).
Arrays and cloneable objects use the clone
method. For your own classes,
it is up to you to define this method and use deep cloning if appropriate.
Collection
s and Map
s are wrapped by immutable wrapper classes (but not deeply cloned!).
Attempts to update them will result in an UnsupportedOperationException
.
@Immutable
classes are allowed but for an
otherwise possible mutable property type, an error is thrown.
equals
or hashCode
methods.
Use at your own risk!
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