Re: Constness with standard containters of pointers

From:

"Victor Bazarov" <v.Abazarov@comAcast.net>

Newsgroups:

comp.lang.c++

Date:

Fri, 16 May 2008 19:15:04 -0400

Message-ID:

<sKSdnUwFd73miLPVnZ2dnUVZ_tninZ2d@comcast.com>

James Kanze wrote:

On 16 mai, 19:29, Victor Bazarov <v.Abaza...@comAcast.net> wrote:

Javier wrote:

[..] if I have:

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

 private:
 std::list 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 const A::getList() const
 {
 return std::list( m_list.begin(), m_list.end() ) ;
 }

The OP had the function returning a _reference_.

What about the conversion from "std::list" 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.

I believe we use the term "convert" overloadedly here. Just as
much as one can "convert" an int into a C string...

V
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