Over a million developers have joined DZone.
{{announcement.body}}
{{announcement.title}}

Closure Composition in Groovy

DZone's Guide to

Closure Composition in Groovy

· Java Zone
Free Resource

Download Microservices for Java Developers: A hands-on introduction to frameworks and containers. Brought to you in partnership with Red Hat.

This is a short blog post about a feature of Groovy closures I discovered a few days ago: Closure Composition.

With Closure Composition we can chain closure calls within a single closure.

Assume we have the following three closures:

def square = { it * it }
def plusOne = { it + 1 }
def half = { it / 2 }

Now we can combine those closures using the << or >> operators:

def c = half >> plusOne >> square

If we now call c() first half() will be called. The return value of half() will then be passed toplusOne(). At last square() will be called with the return value of plusOne().

println c(10) // (10 / 2 + 1)² -> 36

We can reverse the call order by using the << operator instead of >>

def c = half << plusOne << square

Now square() will be called before plusOne(). half() will be called last.

println c(10) // (10² + 1) / 2 -> 50.5


Download Building Reactive Microservices in Java: Asynchronous and Event-Based Application Design. Brought to you in partnership with Red Hat

Topics:

Published at DZone with permission of Michael Scharhag, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

{{ parent.title || parent.header.title}}

{{ parent.tldr }}

{{ parent.urlSource.name }}