// retain the new value (if any) outside the lock.
uintptr_t old_policy = 0; // NOTE: old_policy is always assigned to when old_value is non-nil.
id new_value = value ? acquireValue(value, policy) : nil, old_value = nil;
// retain the new value (if any) outside the lock.
uintptr_t old_policy = 0; // NOTE: old_policy is always assigned to when old_value is non-nil.
id new_value = value ? acquireValue(value, policy) : nil, old_value = nil;