Re: [boost] boost::scoped_array::release?

From: Sebastian Redl (sebastian.redl_at_[hidden])
Date: 2006-03-09 15:03:38

Ralf W. Grosse-Kunstleve wrote:

>In contrast to the STLport implementation I use this approach to implement the
>copy constructor (and similarly for the assignment operator):
>
>  class auto_array
>  {
>      mutable T* ptr;
>
>      auto_array(auto_array const& other)
>      {
>        ptr = const_cast<auto_array*>(&other)->release();
>      }
>  };
>
>
>I know it works on a large number of platforms (several versions of EDG, VC,
>g++). valgrind also didn't have any complaints. Is the approach also OK from a
>theoretical viewpoint?
>
I don't know about STLport's approach, but const-casting the parameter 
is definitely not OK from a theoretical viewpoint. Your const parameter 
is a promise that you won't modify the parameter, but then you go ahead 
and do it anyway.
You should make the parameter non-const, like the GNU C++ library does 
with auto_ptr:
auto_ptr(auto_ptr& __a) throw() : _M_ptr(__a.release()) { }

Sebastian Redl