// calling a method with a fixed name and

// argument type on a (possibly) changing object

// as fast as possible

static Symbol symbol_bla = toSymbol("bla");

sclass CallSiteCache_oneArg {

  Class targetClass;

  Class argType; // set to null if target method is not overloaded

  MethodHandle mh;

}

static WeakReference<CallSiteCache_oneArg> callSite1_cache;

if (o != null) {

  var cache == getWeakRef(callSite1_cache);

  Class c = o.getClass();

  Class argType = _getClass(arg);

  if (cache != null && cache! == c

    && (cache.argType == null || cache.argType == argType)) {}

  else {

    cache = findCachedMethod(x, symbol_bla, arg);

    callSite1_cache = weakRef(cache);

  }

  invoke(cache.mh, arg);

}