From Mechanism to Method: Function Follows Form
By Kelvin Henney, November 01, 2000
Of all the features of C++ that can affect source code readability, operator overloading is one of the most powerful. Operator overloading can render otherwise well-written code obscure; on the other hand, it makes possible many important idioms - smart pointers, function objects, and iterators, to name a few. Kevlin Henney shows us another good application of operator overloading: a remember_function that bundles a target object together with a member function pointer for later callback
November 2000 C++ Experts Forum/From Mechanism to Method/Listing 3
class function_ptr
{
public:
function_ptr()
: body(0)
{
}
template<typename nullary_function>
function_ptr(nullary_function function)
: body(new adaptor<nullary_function>(function))
{
}
~function_ptr()
{
delete body;
}
...
private:
class callable
{
public:
virtual ~callable()
{
}
virtual callable *clone() const = 0;
virtual void call() = 0;
};
template<typename nullary_function>
class adaptor : public callable
{
public:
adaptor(nullary_function function)
: adaptee(function)
{
}
virtual callable *clone() const
{
return new adaptor(adaptee);
}
virtual void call()
{
adaptee();
}
nullary_function adaptee;
};
callable *body;
};
