Created
April 7, 2011 15:41
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Calling private methods in Scala
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// Usage: | |
// p(instance)('privateMethod)(arg1, arg2, arg3) | |
class PrivateMethodCaller(x: AnyRef, methodName: String) { | |
def apply(_args: Any*): Any = { | |
val args = _args.map(_.asInstanceOf[AnyRef]) | |
def _parents: Stream[Class[_]] = Stream(x.getClass) #::: _parents.map(_.getSuperclass) | |
val parents = _parents.takeWhile(_ != null).toList | |
val methods = parents.flatMap(_.getDeclaredMethods) | |
val method = methods.find(_.getName == methodName).getOrElse(throw new IllegalArgumentException("Method " + methodName + " not found")) | |
method.setAccessible(true) | |
method.invoke(x, args : _*) | |
} | |
} | |
class PrivateMethodExposer(x: AnyRef) { | |
def apply(method: scala.Symbol): PrivateMethodCaller = new PrivateMethodCaller(x, method.name) | |
} | |
def p(x: AnyRef): PrivateMethodExposer = new PrivateMethodExposer(x) |
some method names are of the form: org$apache$spark$sql$execution$command$ShowCreateTableCommand$$escapeSingleQuotedString
p(instance)('escapeSingleQuotedString)("aaa")
java.lang.IllegalArgumentException: Method escapeSingleQuotedString not found
Workaround like so:
val method = methods.find(_.getName.split("\\$\\$") contains methodName).getOrElse(
throw new IllegalArgumentException("Method " + methodName + s" not found, available: ${methods.map(_.getName).mkString(", ")}"))
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@leobenkel demo like this?