How to get groovy to evaluate ${sth} when stored in string? - groovy

Question

I'm getting a text which contains ${somethingElse} inside, but it's just a normal String.
I've got a class:
class Whatever {
def somethingElse = 5
void action(String sth) {
def test = []
test.testing = sth
assert test.testing == 5
}
}
Is it possible with groovy?
EDIT:
my scenario is: load xml file, which contains nodes with values pointing to some other values in my application. So let's say I've got shell.setVariable("current", myClass). And now, in my xml I want to be able to put ${current.someField} as a value.
The trouble is, that the value from xml is a string and I can't evaluate it easily.
I can't predict how these "values" will be created by user, I just give them ability to use few classes.
I cannot convert it when the xml file is loaded, it has to be "on demand", since I use it in specific cases and I want them to be able to use values at that moment in time, and not when xml file is loaded.
Any tips?

Answer 1

One thing you could do is:
class Whatever {
def somethingElse = 5
void action( String sth ) {
def result = new groovy.text.GStringTemplateEngine().with {
createTemplate( sth ).make( this.properties ).toString()
}
assert result == "Number 5"
}
}
// Pass it a String
new Whatever().action( 'Number ${somethingElse}' )

Answer 2

At first, what we did, was used this format in xml:
normalText#codeToExecuteOrEvaluate#normalText
and used replace closure to regexp and groovyShell.evaluate() the code.
Insane. It took a lot of time and a lot of memory.
In the end we changed the format to the original one and crated scripts for each string we wanted to be able to evaluate:
Script script = shell.parse("\""+stringToParse+"\"")
where
stringToParse = "Hello world # ${System.currentTimeMillis()}!!"
Then we were able to call script.run() as many times as we wanted and everything performed well.
It actually still does.