From: daniel.kruegler@googlemail.com   
      
   On 2011-12-09 18:24, Nevin ":-]" Liber wrote:   
   > In article,   
   >   Daniel Krügler  wrote:   
   >   
   >> This is true, but not much of a problem, because std::shared_ptr (as   
   >> std::unique_ptr) implement operator<  in terms of less<>  of the underlying   
   >> pointer:   
   >   
   >> And the less<>  specialization for pointers *does* induce a total order (see   
   >> 20.8.5 p8).   
   >   
   > But less<>  of the underlying pointer implements an *unspecified* strict   
   > weak ordering, which is just another way of saying that the actual order   
   > itself is meaningless.   
      
   I do not understand this part of your reply: As I quoted above the   
   less<> specialization for pointers does induce a total order, which is   
   also a strict weak order. It is unspecified, yes, but why should you   
   care? There does not exist a guaranteed way to order arbitrary pointer   
   values. I don't see the implication, that this ordering is   
   "meaning-less". It should be sufficient to hold your pointer values in a   
   std::map.   
      
   Unspecified ordering has still it's values, just look at operator< for   
   std::error_category, std::error_code, std::type_info (and therefore for   
   std::type_index) or for thread::id. This is not different from ordering   
   of (arbitrary) pointer values.   
      
   Greetings from Bremen,   
      
   Daniel Krügler   
      
      
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