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Re: would you consider this function const?

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In article <jcai9t$ee9$1@dont-email.me>,
Victor Bazarov  <v.bazarov@comcast.invalid> wrote:
>
>IME 'const_cast' is good only for one thing: to add const where one 
>needs an overload resolution to go a particular way.  Any other use of 
>'const_cast' is an instance of abuse.  That's just IME, of course.

I would tolerate const_cast inside a method when conceptually, a
method is const (i.e. does not conceptually change the object) but due
to implementation details, the object internal needs to be modified. 

I very rarely see a reason to use it.  But for example, some peoples
are fans of delaying initialisation using a pattern like:

class A
{
public:
   A(): m_initDone(false), ... {};
   std::string foo()  const
   {
      if(!m_initDone)
      {
         const_cast<A *>(this)->init();
      }
      // do the work
   }
private:
   void init() {...};
   bool m_initDone;
   // other member variables
}

I am not a big fan of the above but this would be an example where
const_cast allow an object to modify its internals without breaking
the concept that the object has not changed.  

Unfortunately, most of the time const_cast is used to cast-away
constness from code that is const-correct to interface with
const-incorrect code when the correct thing to do would be fix the
const-incorrect code :-( (Actually, most of the time I see it, C-style
hard casts are being used which is even worse).


Yannick

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would you consider this function const? john <gh14tq5@yahoo.com> - 2011-12-14 10:17 -0500
  Re: would you consider this function const? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-12-14 11:19 -0500
    Re: would you consider this function const? john <gh14tq5@yahoo.com> - 2011-12-15 08:10 -0500
      Re: would you consider this function const? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-12-15 08:21 -0500
        Re: would you consider this function const? john <gh14tq5@yahoo.com> - 2011-12-15 08:44 -0500
          Re: would you consider this function const? Leigh Johnston <leigh@i42.co.uk> - 2011-12-15 14:07 +0000
            Re: would you consider this function const? Leigh Johnston <leigh@i42.co.uk> - 2011-12-15 14:14 +0000
          Re: would you consider this function const? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-12-15 09:11 -0500
            Re: would you consider this function const? john <gh14tq5@yahoo.com> - 2011-12-15 09:30 -0500
              Re: would you consider this function const? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-12-15 10:06 -0500
                Re: would you consider this function const? john <gh14tq5@yahoo.com> - 2011-12-15 12:42 -0500
                Re: would you consider this function const? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-12-15 13:32 -0500
    Re: would you consider this function const? yatremblay@bel1lin202.(none) (Yannick Tremblay) - 2011-12-19 18:16 +0000
      Re: would you consider this function const? Tobias Müller <troplin@bluewin.ch> - 2011-12-19 19:05 +0000
        Re: would you consider this function const? Joshua Maurice <joshuamaurice@gmail.com> - 2011-12-19 14:36 -0800
          Re: would you consider this function const? Tobias Müller <troplin@bluewin.ch> - 2011-12-20 06:28 +0000
            Re: would you consider this function const? Joshua Maurice <joshuamaurice@gmail.com> - 2011-12-19 23:48 -0800

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