[boost] Re: compare

From: Jan Langer (jan_at_[hidden])
Date: 2003-03-28 23:51:34

Gennaro Prota wrote:
> Ok. This is my last post in this thread. Let me just add that your
> conversion function to bool, together with the default constructor you
> provide, lets the user take the "result of the comparison" without
> actually doing any call to operator().

yes. but i cant see a problem with that. it is just as doing 
lexicographic_compare with two empty sequences.

> class compare
> {
> public:
>     enum result { minus, equiv, plus };
> 
> private:
>     class R {
> [...]
 >        operator result() const { return v_; }
> 
>     };
> 
>     mutable R result_;
> [...]
> };

ok. assuming that we want to convey all three states to the public. and 
i want the bool-conversion semantik to be the same. why do you think an 
implicit conversion to result is the right way?

i can also think of an function
        result get_result () const { return v_; }

or three single functions for each state
        bool minus () const;
        bool plus () const;
        bool equiv () const;

another idea would be to make it two classes compare and compare_3way. 
one with the bool conversion and one with the implicit operator result.

jan

-- 
jan langer ... jan_at_[hidden]
"pi ist genau drei"