in a singleton class, if a member function isn't dependent on whether the instance has been created or not, you can define it as static. so, user can call it use class name directly. take the above for example:
define the someFn as static, so user can call it as myClass::someFn(); instead of "
myClass * ptr = myClass::getInstance(); ptr->someFn";
if a member function is dependent on the instance. it's better not to define it as static. otherwise ,you should check and initialize the instance in this function.