Gradle Goodness: Methods Generated for Setting Task Properties
If we create our own tasks in Gradle, we usually extend from the DefaultTask or a subclass of DefaultTask. This is different from the setProperty and getProperty methods already added by Groovy, but how? Let's look at the details.
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Join For FreeIf we create our own tasks in Gradle, we usually extend from the DefaultTask
or a subclass of DefaultTask
. The tasks that are included with Gradle also extend from this class. Gradle will create a proxy class for the actual class implementation and adds (among other things) also a property setter method. The method has the name of the property and has a single argument of the same type as the property. It is different from the setProperty and getProperty methods already added by Groovy. For example, if we have a task with a property with the name message
of type String
then Gradle will add the method message(String)
to the proxy class.
In the following example task, we have one property, user
:
// File: buildSrc/src/main/groovy/com/mrhaki/gradle/Hello.groovy
package com.mrhaki.gradle
import org.gradle.api.DefaultTask
import org.gradle.api.tasks.TaskAction
class Hello extends DefaultTask {
String user
@TaskAction
void sayHello() {
println "Hello $user, how are you doing?"
}
}
With the following test, we can check that the method user(String)
is actually created and we can use it to set a value for the user
property:
// File: src/test/groovy/com/mrhaki/gradle/HelloTaskSpec.groovy
package com.mrhaki.gradle
import org.gradle.api.Project
import org.gradle.testfixtures.ProjectBuilder
import spock.lang.Specification
import spock.lang.Subject
class HelloTaskSpec extends Specification {
@Subject
private Hello task
private Project project = ProjectBuilder.builder().build()
def "user() method is generated to set user property"() {
when:
task = project.task('helloSample', type: Hello) {
// Gradle generates proxy class to allow
// 'setter(value)' methods for properties.
// In this case we invoke user(String),
// which maps to setUser(String).
user 'sample'
}
then:
task.user == 'sample'
}
def "Groovy syntax property assignment to set user property"() {
when:
task = project.task('helloSample', type: Hello) {
// Groovy syntax for setUser(String).
user = 'sample user'
}
then:
task.user == 'sample user'
}
}
The following build file has two tasks of type Hello
where we use the user(String)
method and a property assignment:
import com.mrhaki.gradle.Hello
task helloMrhaki(type: Hello) {
user = 'mrhaki'
}
task helloHubert(type: Hello) {
user 'Hubert'
}
The idea of this post came from watching a great presentation by Vitaliy Zasadnyy about Gradle plugins during a Mashup Gradle/Android Meetup.
Published at DZone with permission of Hubert Klein Ikkink, DZone MVB. See the original article here.
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