Is there a way to split/factor out common parts of Gradle build

Question

We have several independent builds (each independent build is a multi-project build). The main build scripts become quite big as we have a set of common tasks reused by subprojects as well as there is a lot of repeation between indepedent builds. What we are looking for is:

1. A way to split main build file into smaller files
2. A way to reuse some parts of the build in other independent builds

What is the best way to achieve that in Gradle?

Answer 1

Gradle 0.9 allows you to import a build script from another build script. Have a look at: Configuring the project using an external build script. Basically it's apply from: 'other.gradle'.

One thing the user guide doesn't mention is that the 'from' parameter can be a URL, so you can make your shared scripts available via HTTP somewhere (eg your subversion repository), and import them from multiple builds.

Answer 2

The solution I found implies mapping the things you have in your other.gradle file.

def getVersionName = { ->
    def stdout = new ByteArrayOutputStream()
    exec {
        commandLine 'git', 'describe', '--tags'
        standardOutput = stdout
    }
    return stdout.toString().trim()
}
ext{
    VERConsts = [:]
    VERConsts['NAME'] = getVersionName()
    VERConsts['NAME_CALL'] = getVersionName
}

Then, in your build.gradle file:

apply from: 'other.gradle'
// ...
android {
    defaultConfig {
        versionName VERConsts['NAME_CALL']()
        // or
        versionName VERConsts['NAME']
    }
}

Then, the versionName will have the call result.

Notes:

• VERConsts['NAME'] = getVersionName() will call getVersionName() and store its result. Using it in your script e.g. versionName VERConsts['NAME'] will then assign the stored value.
• VERConsts['NAME_CALL'] will instead store a reference to the function. Using VERConsts['NAME_CALL']() in your script will actually call the function and assign the result to your variable

The former will result in the same value being assigned across the script while the latter may result in different values (e.g. if someone pushes another version while your script is running).