Details
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Bug
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Status: Open
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Major
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Resolution: Unresolved
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1.7.1, 1.7.4, 1.8.2
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None
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Can be reproduced on a Groovy Console on any of the affected versions, e.g., 1.7.4
Description
When using the metaClass of a Java class to override a method, that change doesn't take effect on new instances of that class, until the metaClass on the instance is changed (though the change doesn't need to have any relation to the overriden method):
String.metaClass.toString = { -> return "meta method" }
def s = new String("original string")
println s.toString()
s.metaClass.randomChange = {}
println s.toString()
The expected output would be
meta method meta method
However, the actual output is
original string meta method
It seems that the instance metaClass doesn't recognize the change until it has been changed itself.
My first intuition was that there is some caching involved and the change to the instance metaClass invalidates the cached metaClass and the overriden method is pulled in afterwards, but fiddling with InvokerHelper.metaRegistry.setMetaClass() didn't change anything either.
A simple unit test would be
String.metaClass.toString = { -> return "meta method" }
def s = new String("original string")
assert "meta method", s.toString()