C++ for Scientists - Technische Universität Dresden

7.4. FUNCTIONAL PROGRAMMING 211
}
};
stream ≪ func(arg);
The only thing we have to do by now is to write an appropriate object generator around in
order to persuade the C ++ syntax to accept something like the first line of code of this chapter.
template
output function object
operator≪ (StreamType stream, FunctionObjectT func)
{
return output function object(stream, func);
}
By using these objects it is almost possible to offer a convenient way to write the already
presented for each - code snippet. The remaining adaptation is to use a so-called unnamed
object instead of the dereferenced iterator arg1.
argument 1 function object arg1;
std::for each(vec.begin(), vec.end(), std::cout ≪ arg1);
By creating a collection of functor objects 2 a functional programming style can be mimiced.
As can then be obvserved, polymorphism, which has to be especially provided in the imperative
world, comes naturally to the functional paradigm as no specific assumptions about data types
are required, only conceptual requirements need to be met.
2 Instead of creating all of these functors again, the Boost Phoenix library or the C++ TR1 lambda library
can be used.