For example, if I execute a Groovy script, which modifies the String meta class, adding a method foo()
GroovyShell shell1 = new GroovyShell();
shell1.evaluate("String.metaClass.foo = {-> delegate.toUpperCase()}");
when I create a new shell after that and execute it, the changes are still there
GroovyShell shell2 = new GroovyShell();
Object result = shell2.evaluate("'a'.foo()");
Is there a way to undo all meta class changes after executing the GroovyShell? I tried
shell1.getClassLoader().clearCache();
and
shell1.resetLoadedClasses();
but that did not make a change.
You can use
GroovySystem.metaClassRegistry.removeMetaClass(String.class);
to revert all changes made to the String meta class.
Alternatively you could only change the meta class of a certain String instance, thus not all instances of String would be affected.
You can use MetaClassRegistryCleaner too.
Before doing some metaclass changes, you can do
MetaClassRegistryCleaner registryCleaner = MetaClassRegistryCleaner.createAndRegister()
GroovySystem.metaClassRegistry.addMetaClassRegistryChangeEventListener(registryCleaner)
And when you want to reset the metaclass changes to the state they were earlier.
You can do
registryCleaner.clean()
GroovySystem.metaClassRegistry.removeMetaClassRegistryChangeEventListener(registryCleaner)
This way you can reset all the metaclass changes made during the duration.
I realise that this is a somewhat older question, but it's the first result on Google when I was searching for exactly the same issue.
The solution I chose was to put groovy into a new classloader (by using plexus-classworlds), so when the script is finished, the classloader is disposed (and so any changes to the metaclass are also disposed).
