Re: Constness with standard containters of pointers

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Fri, 16 May 2008 14:21:44 -0700 (PDT)
Message-ID:
<03ccfb4c-1ebf-4edd-8435-9d5b60adb123@d77g2000hsb.googlegroups.com>
On 16 mai, 19:29, Victor Bazarov <v.Abaza...@comAcast.net> wrote:

Javier wrote:

[..] if I have:

     class A
     {
     public:
          ...
          std::list< B * > & getList() { return m_list; };
          const std::list< const B * > & getList() const
{ ...???... };

     private:
          std::list< B * > m_list;
     }

What should I write in the const version of "getList()"?


You can't do much there. list<T> and list<const T> are
different types and cannot be converted into each other.


That's not quite true. There's nothing to stop you from writing
something like:

    std::list< B const* > const A::getList() const
    {
        return std::list< B const* >( m_list.begin(), m_list.end() ) ;
    }

What about the conversion from "std::list< B * >" to "const
std::list< const B * >"... The second const changes the
template argument so, is it a different type?


Yep.


But the STL is designed so that you can convert any type of sequence
to
any other type, as long as the contained elements are
convertible. I use this rather regularly for initializations,
but it works generally.

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James Kanze (GABI Software) email:james.kanze@gmail.com
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