Evaluate "Exec" task arguments at execution time

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1

I have 2 Exec tasks. Output from one task should be an input for another:

task bar(type: Exec) {
    commandLine('./someShellScript')
    standardOutput = new ByteArrayOutputStream()
    ext.output = {
        return standardOutput.toString()
    }
}

task foo(type: Exec) {
    dependsOn bar
    commandLine('./someOtherSript,'
                bar.ext.output()) //this is an output from first task
    standardOutput = new ByteArrayOutputStream()
    ext.output = {
        return standardOutput.toString()
    }
}

But after I wrote this, I realized that evaluation of foo's commandLine happens at the configuration stage (bar.ext.output() is called before bar is executed).

How do I make this kind of connection between these 2 Exec tasks when one acts as input for another?

2

You could use a lazy evaluated GString for this.

commandLine './someOtherScript', "${->bar.output()}"
3

Ha! Didnā€™t know about this one! You saved my day! Thanks!

5

Hi,

that works really well for a string, but how would you do for a list? I tried something like


task mytask(type: Exec) {
  def cmd = []

  doFirst {
    cmd.add("ls")
  }

  commandLine { -> cmd }
}

with no success, the closure is called at evaluation time (the example above makes no sense per se, imagine that the list we add to cmd comes from another taskā€™s output)

6

Realistically, the only other option is to use a ā€œconfiguration taskā€, that is, a task whose action configures another task.

task foo(type: Exec) {
  dependsOn 'configureFoo'
}

task configureFoo {
  doLast {
    foo.commandLine = // grab from other task's output
  }
}
7

If anybody sees this 6 years later, here is another option.

tasks.register("foo") {
  doLast {
    exec {
      commandLine(('./someOtherSript,' someFunctionThatNeedsToBeLazy())
    }
  }
}
8

is it possible with kotlin dsl?

9

Using a GString?
No, that is a Groovy thing.
But the arguments are all evaluated lazily using toString().
So you can supply any object that lazily in toString() calculates the value.

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