c753ba84   
   From: dave@boostpro.com   
      
   on Wed Apr 11 2012, cppljevans-AT-gmail.com wrote:   
      
   > On Saturday, April 7, 2012 12:46:32 AM UTC-5, Dave Abrahams wrote:   
   > [snip]   
   >> But if that makes you uneasy, consider:   
   >>   
   >>      union foo   
   >>      {   
   >>          int nVals;   
   >>          boost::aligned_storage<   
   >>              sizeof(int),   
   >>              boost::alignment_of::value   
   >>          >::type align;   
   >>      };   
   >>   
   >> now you could treat the memory starting at &x+1 (where x is of type   
   >> foo) as an array of doubles:   
   > [snip]   
   > Hi Dave,   
   >   
   > IIUC, the purpose of using aligned_storage with the   
   > alignment_of arg is to make sure the union starts at an   
   > alignment suitable for a double.  However, since memory   
   > for the nVals and the array of doubles is to be   
   > allocated with new(as shown by the OP):   
   >   
   >   foo * fooPtr = static_cast(::operator new(memToAlloc));   
   >   
   > and since new always (IIUC) returns memory allocated   
   > at the maximum alignment, I'm wondering why the aligned_storage   
   > and alignment_of are needed.   
      
   It ensures that (fooPtr+1) is aligned appropriately for storing doubles.   
      
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   Dave Abrahams   
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