Exceptional C++: 47 Engineering Puzzles, Programming Problems, and Solutions

Chapter 34. Name Lookup and the Interface Principle—Part 4

Difficulty: 9

We conclude this miniseries by considering some implications of the Interface Principle on name lookup. Can you spot the (quite subtle) problem lurking in the following code?

1. What is name hiding? Show how it can affect the visibility of base class names in derived classes.

2. Will the following example compile correctly? Make your answer as complete as you can. Try to isolate and explain any areas of doubt.

// Example 2: Will this compile? 
//
// In some library header:
namespace N { class C {}; }
int operator+(int i, N::C) { return i+1; }
// A mainline to exercise it:
#include <numeric>
int main()
{
  N::C a[10];
  std::accumulate(a, a+10, 0);
}

Solution

Let's recap a familiar inheritance ...