CODEWITHSUNDEEP
gradle
Liu Nate
Liu Nate

Reputation: 672

What's the design purpose of Gradle doFirst and doLast?

For example I have the Gradle script like:

myTask_A {
    doFirst {
        println "first string"

    }
    doLast {
        println "last string"
    }
}

The following two tasks have exactly the same execution result:

myTask_B {
    doFirst {
        println "first string"
        println "last string"
    }
}

myTask_C {
    doLast {
        println "first string"
        println "last string"
    }
}

What's the design purpose of the the doFirst & doLast as any of above tasks produces the same result?

Upvotes: 47

Views: 23895

Answers (1)

Alpar
Alpar

Reputation: 2897

It has to do with extensibility, reuse and avoiding duplication.

For one built in tasks can be extended like:

task CopyAndThen(type: Copy) {
   doFirst {
      println "this is before the actual copy"
   }
   doLast {
      println "this is after the actual copy"
   }
}

The second common scenario that comes to mind is with multi project builds, where you can have a task definition at the top of the project with common behavior:

allprojects {
    task myTask_a {
        doFirst {...}
    }
}

And then the specific projects can extend that. The task essentially has a list of the Closures that needs to be run and the choice of doFirst or doLast controls to which end of the list the insert goes to.

Upvotes: 49

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