C++ for Scientists - Technische Universität Dresden

218 CHAPTER 7. EFFECTIVE PROGRAMMING: THE POLYMORPHIC WAY
protected:
int handle;
int segment;
topology∗ topo;
};
Here, no class hierarchy is required. It has only be guaranteed, that each data type provides an
implementation of the required method. Below print equal() is written as a function template:
template
void print equal(const VertexType& ve1, const VertexType& ve2)
{
std::cout ≪ std::boolalpha ≪ ve1.equal(ve2) ≪ std::endl;
}
In the code snippet below, the same polymorphic behavior can be seen as in the dynamic
polymorphism example, but without the necessity of inheriting from a common base class.
int main()
{
topology the topo;
}
// ∗∗∗ structured
structured vertex sv1(12, &the topo);
structured vertex sv2(12, &the topo);
print equal(sv1, sv2);
// ∗∗∗ unstructured
unstructured vertex usv1(12, &the topo,1);
unstructured vertex usv2(12, &the topo,2);
print equal(usv1, usv2);
return 0;
Without a pointer mechanisms the compiler can easily optimize these lines, i.e. inline the code.
Additionally exceptions cannot occur at run time.
Due to its characteristics, static polymorphism in C++ is best at:
• Uniform manipulation based on syntactic and semantic interface: Types that obey a
syntactic and semantic interface can be treated uniformly.