From: Steven Watanabe (steven_at_[hidden])
Date: 2006-08-03 15:13:45
AMDG
Alexander,
>For the latter I'm thinking of the following approach:
>
> struct plus : function<plus, anyT (anyT const&, anyT const&)>
> {
> int entry(id<1>, int, int) const;
> double entry(id<2>, double, int) const;
> // ...
> std::string entry(id<100>, std::string const&, char) const;
> // ...
> };
>
>
>
How do you detect the end of the entries?
I can't think of anything better in general but here are
some other possibilities that might be more convenient:
struct plus : function<plus, anyT (anyT const&, anyT const&)>
{
typedef boost::mpl::vector<
int (int, int),
double (double, int),
//...
string (string const&, char),
//...
> entry_functions;
template<class T, class U>
T entry(T t, U u) const;
};
or this:
struct plus : function<plus, anyT (anyT const&, anyT const&)>
{
typedef boost::mpl::vector<int, double, string const&>
first_any_argument_types;
typedef boost::mpl::vector<int, char> second_any_argument_types;
template<class T, class U>
T entry(T t, U u) const;
};
Of course this one only works when you want every
possible combination of the types.
In any case I agree that there should be a backup to use if
the types passed in don't match one of the signatures provided.
Maybe something like allowing any one of the arguments
to be unbounded.
typedef boost::mpl::vector_c<int, 1, 2>
possibly_unbounded_any_arg_indexes;
Another way would be to require all the types to be the same
when at least one of them doesn't match.
In Christ,
Steven Watanabe