upcasting

I have a plain old CRPT (please don't get distracted by access restrictions - the question is not about them): template<class Derived> class Base { void MethodToOverride() { // generic stuff here } void ProblematicMethod() { static_cast<Derived*>(this)->MethodToOverride(); } }; that is as usual intended to be used like this: class ConcreteDerived : public Base<ConcreteDerived> { void MethodToOverride() { //custom stuff here, then maybe Base::MethodToOverride(); } }; Now that static_cast bothers me. I need a downcast (not an upcast), so I have to use an explicit cast. In all reasonable cases

I Knew there are plenty of articles/questions in stackoverflow describing about upcasting and downcasting in Java. And I knew what is upcasting and downcasting. But my question is not specfic to that. Upcasting - Conversion from child to parent - Compiler takes care. No cast is required Downcasting - Conversion from parent to child - Explicit cast is required public class Animal { public void getAnimalName(){ System.out.println("Parent Animal"); } } public class Dog extends Animal{ public void getDogName(){ System.out.println("Dog"); } } public static void main(String[] args) { Dog d = new Dog

I have the following sample code: class Serializable {}; class MyData : public Serializable {}; void GetData( Serializable& ) {} template<typename T> void GetData( T& data ) { std::istringstream s{"test"}; s >> data; } int main() { MyData d; GetData(d); } ( Live Sample ) Based on overload resolution rules, the non-template version should be preferred because the base class is of type Serializable . However, I expect SFINAE to kick in when there are errors in the template version when it is instantiated for overload resolution (because if the >> operator is not defined for a type, it should not

There is a method which receives an argument of type Collection and it needs to use some of the methods that are found in the List class when it does work with that argument. Is up-casting expensive in terms of speed? List<Stuff> list = (List<Stuff>) collection; I would also like to note that the collection object is never used after this, only the list , and that this will be compiled and run on Oracle Java 1.6. Serious answers are given by actual benchmarks. For example, I used this jmh -targeting code: public class Benchmark1 { static final List<Integer>[] lists = new List[10000]; static {

I have a class defined by an interface public interface Test { void testMethod(); } Test test = new TestImpl(); public class TestImpl implements Test { @Override public void testMethod() { //Nothing to do here } public void anotherMethod() { //I am adding this method in the implementation only. } } How can I call anotherMethod? test.anotherMethod(); //Does not work. I want to be able to define a few methods in the implementation only because in my production code, the Test interface covers a pretty broad spectrum of classes and is implemented by multiple classes. I use methods defined in the

This question already has an answer here: Can I cast a derived class to a private base class, using C-style cast? 3 answers Say we have this code class A { public: A() : x(1) {} virtual ~A() {} int x; }; class B { public: B() : y(2) {} virtual ~B() {} void g() { cout << "B::" << y << endl; } int y; }; class C : private A, private B { public: void f() { B* p = static_cast<B*>( this ); p->g(); } }; int main() { C c; ((B*)&c)->g(); return 0; } The C style cast in the main function cannot be correctly expressed in terms of the C++ casts ( static_cast , dynamic_cast , reinterpret_cast ). But what