How to use gradle extension correctly in plugins using GradleBuild task? - gradle

Question

EDIT : I rephrased my question in taken the propositon of David M. Karr into account.
I am writing a gradle plugin. This plugin is launching a task extending GradleBuild. The external gradle build file needs some info as parameters. These parameters are given in project extension.
Plugin code
class MyPlugin implements Plugin<Project> {
def mExt
void apply(Project project) {
mExt = project.extensions.create('myext',MyExt)
project.task('myTask', type:GradleBuild){
def param = new StartParameter()
param.setProjectProperties([target:getTarget()])
// Problem here
startParameter = param
buildFile = getMyBuildPath()
tasks = [
'build',
'generateDebugJavadocJar'
]
}
}
def getMyBuildPath(){
...
}
// Problem here
def getTarget(){
return {mExt.target}
}
}
class MyExt {
def String target = "uninitialised"
}
Gradle build file :
apply plugin : 'com.example.myplugin'
ext{
target = "myTarget"
}
External Gradle build file :
task build(){
println project.target
}
If I put a closure in getTarget(), println project.target shows the closure and not the string.
If I don't put the closure :
// Problem here
def getTarget(){
return mExt.target
}
Then I got "uninitialised" instead of "myTarget".
How can I get the value of myext.target here ?
I am using gradle 2.3

Answer 1

Try this:
Define an instance variable called "myext", of type "MyExt".
In the "apply" method, do this:
myext = project.extensions.create('myext',MyExt)
In the "getTarget" method, return "myext.target".

Answer 2

I have succeeded in getting what I wanted to in using project.afterEvaluate method. Thanks to this question
1) In gradle build task, startParameter.projectProperties is waiting for a map, not a closure. So the idea to put a closure for a lazy definition cannot work.
2) If I put directly in my plugin a reference to mExt.target or project.myext.target, then the initial value is set. The value put in my build.gradle file is not used because the plugin is already evaluated.
3) project.afterEvaluate() solve my problem. The closure ends configuring myTask in using the project's extension.
void apply(Project project) {
project.extensions.create('myext',MyExt)
project.task('myTask', type:GradleBuild){
buildFile = getMyBuildPath()
tasks = [
'build',
'generateDebugJavadocJar'
]
}
project.afterEvaluate { proj ->
proj.myTask.startParameter.projectProperties = [target:proj.myext.target]
}
}