For Gradle users it is important to understand how Groovy deals with script variables. Groovy has two types of script variables. One with a local scope and one with a script wide scope.
Example B.1. Variables scope: local and script wide
scope.groovy
String localScope1 = 'localScope1' def localScope2 = 'localScope2' scriptScope = 'scriptScope' println localScope1 println localScope2 println scriptScope closure = { println localScope1 println localScope2 println scriptScope } def method() { try {localScope1} catch(MissingPropertyException e) {println 'localScope1NotAvailable' } try {localScope2} catch(MissingPropertyException e) {println 'localScope2NotAvailable' } println scriptScope } closure.call() method()
Output of gradle
> gradle localScope1 localScope2 scriptScope localScope1 localScope2 scriptScope localScope1NotAvailable localScope2NotAvailable scriptScope
Variables which are declared with a type modifier are visible within closures but not visible within methods. This is a heavily discussed behavior in the Groovy community. [27]
It is important to keep in mind that Gradle has a distinct configuration and execution phase (see Chapter 55, The Build Lifecycle).
Example B.2. Distinct configuration and execution phase
build.gradle
def classesDir = file('build/classes') classesDir.mkdirs() task clean(type: Delete) { delete 'build' } task compile(dependsOn: 'clean') << { if (!classesDir.isDirectory()) { println 'The class directory does not exist. I can not operate' // do something } // do something }
Output of gradle -q compile
> gradle -q compile The class directory does not exist. I can not operate
As the creation of the directory happens during the configuration phase, the
clean
task removes the directory during the execution phase.
[27] One of those discussions can be found here: http://groovy.329449.n5.nabble.com/script-scoping-question-td355887.html