Exceptional C++ Style 40 New Engineering Puzzles, Programming Problems, and Solutions

Chapter 5. Flavors of Genericity, Part 1: Covering the Basis [sic]

Difficulty: 4

To get our feet wet before delving into Item 6, consider this simple example of flexible generic code in C++. The code examples in this Item and the next are taken from Exceptional C++ [Sutter00, page 42].

JG Question

1. “C++ templates provide compile-time polymorphism.” Explain.

Guru Question

1. What are the semantics of the following function? Be as complete as you can, and be sure to explain why there are two template parameters and not just one.

   template <class T1, class T2>
   void construct(T1* p, const T2& value) {
    new (p) T1(value);
   }
   

Solution

1. “C++ templates provide compile-time polymorphism.” Explain.

When we think of polymorphism in an object-oriented world, we think of ...