Re: How to specially treat the beginning of a type list?
* Thomas J. Gritzan:
PengYu.UT@gmail.com wrote:
The line with the comment "// redundant" is redundant in the sense
that is never used in the main program. However, removing that line
will invalidate the program. I'm wondering if there is any way to
intelligently remove that line while still leaving the program
compilable.
Thanks,
Peng
#include <iostream>
#include <boost/mpl/fold.hpp>
#include <boost/mpl/vector.hpp>
#include <boost/mpl/placeholders.hpp>
class base {
public :
virtual ~base() {}
virtual void accept(base& b) = 0 ;
void visit() { } // redundant
};
template <typename Base, typename T>
class visitor : public Base {
public :
virtual void visit(T &) = 0 ;
using Base::visit;
};
Remove the "using" declaration above, then you also can remove the
declaration of the function void visit().
I'm not familiar with boost::mpl, but I tried what you write because
that seemed sort of obvious, it didn't work, and I decided (after
looking at the documentation) that I had nothing to contribute --
otherwise, it might have been you writing this to me...
Except, to the OP, please explain your code (the fold thing).
I may be wrong, but others than me could possibly benefit from that.
--
A: Because it messes up the order in which people normally read text.
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