Package org.codehaus.groovy.runtime

Class ComposedClosure<V>

  • All Implemented Interfaces:
    GroovyCallable<V>, GroovyObject, java.io.Serializable, java.lang.Cloneable, java.lang.Runnable, java.util.concurrent.Callable<V>
    public final class ComposedClosure<V>
extends Closure<V>
    A wrapper for Closure to support composition. Normally used only internally through the rightShift() and leftShift() methods on Closure.

    Typical usages: 

     def twice = { a -> a * 2 }
 def inc = { b -> b + 1 }
 def f = { x -> twice(inc(x)) } // longhand
 def g = inc >> twice
 def h = twice << inc
 assert f(10) == 22
 assert g(10) == 22
 assert h(10) == 22

 def s2c = { it.chars[0] }
 def p = Integer.&toHexString >> s2c >> Character.&toUpperCase
 assert p(15) == 'F'

 def multiply = { a, b -> a * b }
 def identity = { a -> [a, a] }
 def sq = identity >> multiply
 assert (1..5).collect{ sq(it) } == [1, 4, 9, 16, 25]

 def add3 = { a, b, c -> a + b + c }
 def add2plus10 = add3.curry(10)
 def multBoth = { a, b, c -> [a*c, b*c] }
 def twiceBoth = multBoth.rcurry(2)
 def twiceBothPlus10 = twiceBoth >> add2plus10
 assert twiceBothPlus10(5, 10) == 40
    See Also:
    Serialized Form