It is because name lookup stops if it finds a name in one of your bases. It won’t look beyond in other bases. The function in B shadows the function in A. You have to re-declare the function of A in the scope of B, so that both functions are visible from within B and … Read more
It depends on the order of data member declarations in the class. So a_ will be the first one, then b_ will be the second one in your example.
Reviewing the basic terminology It’s usually good enough – unless you’re programming assembly – to envisage a pointer containing a numeric memory address, with 1 referring to the second byte in the process’s memory, 2 the third, 3 the fourth and so on…. What happened to 0 and the first byte? Well, we’ll get to … Read more
When you add the const keyword to a method the this pointer will essentially become a pointer to const object, and you cannot therefore change any member data. (Unless you use mutable, more on that later). The const keyword is part of the functions signature which means that you can implement two similar methods, one … Read more
1. “What is it?” While std::move() is technically a function – I would say it isn’t really a function. It’s sort of a converter between ways the compiler considers an expression’s value. 2. “What does it do?” The first thing to note is that std::move() doesn’t actually move anything. It changes an expression from being … Read more
Is being able to access data from beyond the grave expected? This is technically known as Undefined Behavior. Don’t be surprised if it offers you a can of beer either.
That’s two-phase lookup for you. Base<T>::NO_ZEROFILL (all caps identifiers are boo, except for macros, BTW) is an identifier that depends on T. Since, when the compiler first parses the template, there’s no actual type substituted for T yet, the compiler doesn’t “know” what Base<T> is. So it cannot know any identifiers you assume to be … Read more
By far the single most important “pattern” to learn and know that’s (nearly) unique to C++ is RAII (Resource Acquisition Is Initialization). Edit: (To answer extra question edited into the question). You use RAII primarily to (semi-)automate resource management. The most obvious use is freeing resources owned by objects when the owning objects go out … Read more
Warning: this is a really long explanation, but hopefully it really explains not only what SFINAE does, but gives some idea of when and why you might use it. Okay, to explain this we probably need to back up and explain templates a bit. As we all know, Python uses what’s commonly referred to as … Read more
All you need to do is declare the class’ new operator private: class X { private: // Prevent heap allocation void * operator new (size_t); void * operator new[] (size_t); void operator delete (void *); void operator delete[] (void*); // … // The rest of the implementation for X // … }; Making ‘operator new’ … Read more