You can register a function that will be called each time a variable is modified or accessed (for embedded components only) by calling UNotifyChange and UNotifyAccess, passing either an UVar or a variable name as first argument, and a member function of your UObject as second argument. This function can take zero or one argument: a UVar & pointing to the UVar being accessed or modified. The notifyChange callback function is called after the variable value is changed, whereas the notifyAccess callback is called before the variable is accessed, giving you the possibility to update its value.