Re: [boost] value_initialized<> uploaded to be Files Section.

From: Anthony Williams (anthwil_at_[hidden])
Date: 2002-08-28 02:24:26

Fernando Cacciola writes:
 > 
 > ----- Original Message -----
 > From: "Anthony Williams" <anthwil_at_[hidden]>
 > To: <boost_at_[hidden]>
 > Sent: Tuesday, August 27, 2002 11:18 AM
 > Subject: [boost] value_initialized<> uploaded to be Files Section.
 > 
 > 
 > > > I've worked-around the 'operator T&() const' problem by providing a
 > strict
 > > > deep-constant non-member get() function, which is presented as the
 > > > recommended idiom.
 > >
 > > If you're going to provide a non-const reference to a member of a const
 > > object, that member had better be mutable....
 > >
 > In general, yes; but in my particular case this has a drawback:
 > 
 > template<class T>
 > struct W
 > {
 >   operator T&()  const { return x ; }
 >   mutable T x ;
 > } ;
 > W<int const> w ; // ERROR: Conflicting type modifiers:  mutable const int x
 > ;

OK, so you need to not specify mutable when T is const. However, leaving it
off when T is not const is undefined behaviour. Looks like a prime target for
partial specialization to me.

Anthony