Re: [boost] borland & boost::indirect_iterator_pair_generator compile error

From: George A. Heintzelman (georgeh_at_[hidden])
Date: 2001-11-21 10:29:42

Henrik,

> I'm struggling with the boost::iterator_adaptors, in detail with the 
> indirect_iterator stuff.
> During my search in the boost group, George A. Heintzelman (message 
> #18183) depicted nearly the same I need. The difference is I'm using 
> shared pointers as the vector template argument.

In that message I supplied a patch, which has been applied in the CVS 
version and  looks like it made it into 1.25.1. Your code compiles with 
g++-3.0.2 with boost version 1.25.0 and my patch applied, with a small 
change indicated below (not relevant to the error you were getting, I 
think). If you applied the patch and it still doesn't compile, then 
there is probably some other problem related to Borland's compiler's 
idiosyncracies...

Good luck,

George Heintzelman
georgeh_at_[hidden]

> //--------------------------------------------------------------------
> #include <iostream>
> #include <boost/utility.hpp>
> #include <boost/smart_ptr.hpp>
> #include <vector>
> #include <boost/iterator_adaptors.hpp>
> #pragma hdrstop
> 
> //--------------------------------------------------------------------
> 
> class foo : boost::noncopyable
> {
>  public:
>     foo(const int a_) : m_a(a_) {}
> 
>     int get() { return m_a; }
> 
>  private:
>     int m_a;
> };
> 
> 
> 
> 
> #pragma argsused
> int main(int argc, char* argv[])
> {
>   typedef boost::shared_ptr<foo>                foo_ptr_t;
>   typedef std::vector<foo_ptr_t>                foo_ptr_vect_t;
>   typedef foo_ptr_vect_t::iterator              vect_iterator;
> 
>   typedef boost::indirect_iterator_pair_generator<
>         vect_iterator,
>         foo, foo&, const foo&,
>         std::random_access_iterator_tag,
>         foo*,
>         const foo*>                             pair_indirectors;
>   typedef pair_indirectors::iterator            indirector;
> 
>   foo_ptr_vect_t v(4);
> 
>   for(std::size_t i=0; i<v.size(); ++i)
>     v[i].swap( foo_ptr_t(new foo(i)) );

This is not legal, since swap must take a non-const reference and you 
are creating a temporary here. g++ 3.0.2 complained. I replaced this 
with;

  for(std::size_t i=0; i<v.size(); ++i) {
    foo_ptr_t new_foo(new foo(i));
    v[i].swap( new_foo );
  }

and it compiled fine.

>     
>   // the following line produces an compiler error 
>   indirector i(v.begin()),
> //  indirector end(v.end());
> 
> //  while(i!=end)
> //  {
> //    std::cout << i->get() << '\n';
> //    ++i;
> //  }
> 
>   return 0;
> }