The order is the order they appear in the class definition – this is from section 12.6.2 of the C++ Standard: 5 Initialization shall proceed in the following order: — First, and only for the constructor of the most derived class as described below, virtual base classes shall be initialized in the order they appear … Read more
Is there a name to describe this idiom? In UML it is called aggregation. It differs from composition in that the member object is not owned by the referring class. In C++ you can implement aggregation in two different ways, through references or pointers. I am assuming it is to prevent the possibly large overhead … Read more
My own rule of thumb : Use a reference member when you want the life of your object to be dependent on the life of other objects : it’s an explicit way to say that you don’t allow the object to be alive without a valid instance of another class – because of no assignment … Read more
David Joyner had the history, here is the reason. The problem when compiling B<T> is that its base class A<T> is unknown from the compiler, being a template class, so no way for the compiler to know any members from the base class. Earlier versions did some inference by actually parsing the base template class, … Read more
You can specify how to initialize members in the member initializer list: BigMommaClass { BigMommaClass(int, int); private: ThingOne thingOne; ThingTwo thingTwo; }; BigMommaClass::BigMommaClass(int numba1, int numba2) : thingOne(numba1 + numba2), thingTwo(numba1, numba2) {}
At the time that x=10 is executed in your example, not only does the class not exist, but the classmethod doesn’t exist either. Execution in Python goes top to bottom. If x=10 is above the classmethod, there is no way you can access the classmethod at that point, because it hasn’t been defined yet. Even … Read more
The order is the order they appear in the class definition – this is from section 12.6.2 of the C++ Standard: 5 Initialization shall proceed in the following order: — First, and only for the constructor of the most derived class as described below, virtual base classes shall be initialized in the order they appear … Read more
The short answer is that they kept the linker about the same, at the expense of making the compiler still more complicated than previously. I.e., instead of this resulting in multiple definitions for the linker to sort out, it still only results in one definition, and the compiler has to sort it out. It also … Read more
You can specify how to initialize members in the member initializer list: BigMommaClass { BigMommaClass(int, int); private: ThingOne thingOne; ThingTwo thingTwo; }; BigMommaClass::BigMommaClass(int numba1, int numba2) : thingOne(numba1 + numba2), thingTwo(numba1, numba2) {}
My own rule of thumb : Use a reference member when you want the life of your object to be dependent on the life of other objects : it’s an explicit way to say that you don’t allow the object to be alive without a valid instance of another class – because of no assignment … Read more