[boost] Re: Re: Mini-review request: aligned_storage.hpp

From: Itay Maman (itay_maman_at_[hidden])
Date: 2002-08-09 06:31:09

Anthony Williams wrote in a message:
>
>I've just had a thought about how to implement the strong guarantee for
variant, at the expense of larger space requirements --- have *two* copies
of >the internals, with a flag to indicate which is valid. Then, when
swapping or assigning, copy construct the value from the other variant into
the unused >space, and destruct the original and switch the flag when
everything is done.
>
>What do people think?
>
>Anthony
>

I don't think it is possible - in the general case - to create two identical
instances of a class.
Consider this class:

// Just another class
struct jac
{
    jac* inst_p_;
    int n_;

   jac(int n = 0)  : n_(n)
   {
     inst_p_ = this;
   }

   jac(const jac& other) : n_(other.n_)

      inst_p_ = this;
   }

   jac* get() { return inst_p_; }
   void set(jac* inst_p) { inst_p_ = inst_p; }
} ;

--
Itay Maman
    itay_maman@_yahoo_.com
    maman_at_il._ibm_.com
This message expresses my personal opinion.