calling gradle "build" task in another project - build

Question

I am only a couple of days into using gradle
In my current build.gradle script I have a task which I would like to call the build task in another project (ie. defined in a different build.gradle somewhere else) after each time it is executed
My question is how do I call a task from another project?
I guess I want to do something like tasks.build.execute() but it doesn't seem to work. I tried this:
commandLine "${rootDir}\\gradle", 'build', 'eclipse'
it at least executed the build and eclipse for my current project just not the master project. Hope my question is clear

Answer 1

Adjust the buildFile path, etc.:
task buildSomethingElse(type: GradleBuild) {
buildFile = '../someOtherDirectory/build.gradle'
tasks = ['build']
}
build.finalizedBy('buildsomethingElse')
Reference: Gradle organizing build logic guide, paragraph 59.5.
You can apply this to another ant project as well, by adding a one line build.gradle file in your ant project that just calls ant, like so:
ant.importBuild 'build.xml'

Answer 2

First read this:
http://gradle.org/docs/current/userguide/multi_project_builds.html
If you have a multi-project build
You need a root project that contains settings.gradle file with something like:
include 'myproject1'
include 'myproject2'
Then you can just make a dependency from one project to another like this:
myproject1/gradle.build
task someOtherTask() << {
println 'Hello'
}
myproject2/gradle.build
task sometask(dependsOn: ':myproject1:someOtherTask') << {
//do something here
}
Or if you want to call a task:
project(':myproject1').tasks.build.execute()
Notice: You have to apply java plugin to make build task available.