Re: [boost] operator++

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2000-10-10 15:58:20

"Erdei, András" wrote on 10/10/2000 4:33 PM
>and found operator++ implemented as
>
>//  incrementable and decrementable contributed by Jeremy Siek
>
>  friend T operator++(T& x, int)
>  {
>    incrementable_type tmp(x);
>    ++x;
>    return tmp;
>  }
>
>a more efficient implemetation can be (stripped off
>the template stuff):
>
>  class proxy
>    {
>    public :
>      operator T const & ( void ) { return real ; }
>      ~proxy() { if ( ! std::uncaught_exception() ) ++real ; } ;
>    private :
>      friend proxy operator++( T & , int ) ;
>      proxy( T & real ) : real( real ) {} ;
>      T & real ;
>    } ;
>
>  proxy
>operator++( T & t , int )
>  {
>    return proxy( t ) ;
>  }

I haven't coded it up and tried it, but I'm concerned that an iterator 
implemented this way might fail with the following code:

MyIterator i, j, k;
...
std::copy(i++, j, k);  // compile-time error?

-Howard