Load closure code from string in Groovy

Question

is it possible to load a closure's code from a string (that may come from a file) in Groovy ?

If you're just looking at evaluating a string (the question is a little vague) this is very similar to http://stackoverflow.com/questions/3264014/equivalent-of-eval-in-groovy — Ted Naleid, May 26 '11 at 02:54
Several solutions you can find here: https://stackoverflow.com/questions/36771508/how-to-dynamically-create-a-groovy-closure-from-a-string-in-java/49896047#49896047 — Naeel Maqsudov, Apr 18 '18 at 09:39

score 16 · Accepted Answer · answered May 25 '11 at 20:07

Did you mean something like this?

groovy:000> sh = new GroovyShell()
===> groovy.lang.GroovyShell@1d6dba0a
groovy:000> closure = sh.evaluate("{it -> println it}")
===> Script1$_run_closure1@59c958af
groovy:000> closure(1)
1
===> null
groovy:000> [1,2,3,4].each { closure(it) }
1
2
3
4
===> [1, 2, 3, 4]
groovy:000>

score 1 · Answer 2 · answered May 25 '11 at 18:51

This should work, not sure if it's the most elegant solution:

ClassLoader parent = getClass().getClassLoader()
GroovyClassLoader loader = new GroovyClassLoader(parent)
Class groovyClass = loader.parseClass("class ClosureHolder {def closures = [{ println 'hello world!' }]}")
def allTheClosures = groovyClass.newInstance()

allTheClosures.closures.each {
    it()
}

Just put your closures inside the list when reading them in.

score -1 · Answer 3 · answered May 25 '11 at 18:39

If you mean something like:

def cl = "{'hello'}" as Closure // fails, can't convert string to closure

No.

However, it appears evaluate() may be an option in this case: http://groovy.329449.n5.nabble.com/creating-closure-from-string-instance-td343089.html

Load closure code from string in Groovy

3 Answers3

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