On Fri, 27 Apr 2001, Angus Leeming wrote:
> I'm trying to get to grip with functors, but it's a long, hard struggle. Can
> some C++ guru explain to me why my approach, below, is a pile of poo?
>
> Many thanks,
> Angus
>
>
>
> // I have some data:
> vector<double> somedata = ...;
>
> // References to some of this data are placed in a list...
> typedef vector<double>::iterator BinItem;
> list<BinItem> bl = ...;
>
> // I want to search this list to find if it contains data of a particular
> value, +- some tolerance value:
> double const tol = 1.0e-08;
> double const desired_value = ...;
>
> find(bl.begin(), bl.end(), CompareWithinTolerance(desired_value, tolerance));
It isn't a function object as far as I can see ;)
e.g. in some other code of mine, a function object looks like this :
/// function object for matching against id
class Message_id_eq : public unary_function<Message, bool> {
int id_;
public:
explicit Message_id_eq(int id) : id_(id) {}
bool operator()(Message * m) const {
return m->id() == id_;
}
};
Hope this helps !
john
--
"Don't follow leaders, watch your parking meters"
- The Bob
