Need Groovy syntax help for generating a Closure from a String

Question

I\'m trying to generate a closure from a string. The code inside the closure references a DSL function build(). The errors I\'m getting imply that Groovy is trying to exec

Answer 1

If you are evaluating the String from your DSL configuration script, you do not need to create a GroovyShell object.

Your script will be run as a subclass of Script which provides a convenience method for evaluating a string with the current binding.

public Object evaluate(String expression)
            throws CompilationFailedException

A helper method to allow the dynamic evaluation of groovy expressions using this scripts binding as the variable scope

So in this case, you'd just need to call evaluate('{ -> build("my job") }').

Answer 2

What about returning the closure from the script?

Eval.me("return { build('my job') } ")

What do you intend using that L:? Returning a map? If is that so, you can use square brackets:

groovy:000> a = Eval.me("[L: { build('test for') }]")
===> {L=Script1$_run_closure1@958d49}
groovy:000> a.L
===> Script1$_run_closure1@958d49

Answer 3

Consider the example below. The key is to specify, explicitly, a closure without parameters.

def build = { def jobName ->
    println "executing ${jobName}"
}

// we initialize the shell to complete the example
def sh = new GroovyShell()
sh.setVariable("build", build)

// note "->" to specify the closure
def cl = sh.evaluate(' { -> build("my job") }')

println cl.class
cl.call()

Answer 4

In addition to Michael Easter's answer, you could also pass the script's binding through to the GroovyShell

def build = { ->
  "BUILD $it"
}

def shell = new GroovyShell( this.binding )
def c = shell.evaluate( "{ -> build( 'tim_yates' ) }" )

c()