///////////////////////////////////////////////////
// MT4Q5.cpp - Assert                            //
//                                               //
// Jim Fawcett, CSE687 - Midterm, Spring 2010    //
///////////////////////////////////////////////////

#include <exception>
#include <iostream>

// this class simply provides a name to be 
// announced when an assertion fails.

class Test 
{ 
public:
  virtual ~Test() {}
  std::string what() 
  { 
    std::string temp = typeid(*this).name();
    temp += std::string(" failed"); 
    return temp;
  }
};

// Assertion class

template<class E>
class Assert
{
public:
  template<class A>
  static void that(A a)
  {
    if(!a)
      throw E();
  }
};

class Test_Alloc : public Test { };

class Widget { };

void main()
{
  std::cout << "\n  MT4Q5 - Assert throws Exception";
  std::cout << "\n =================================";

  Widget* pWidget = 0;

  // some code that tries to allocate a widget

  try {
    Assert<Test_Alloc>::that(pWidget != 0);
  }
  catch(Test_Alloc& ta)
  {
    std::cout << "\n\n  "  << ta.what().c_str() << "\n\n";
  }
}