🚀 go-pugleaf

|> This is a terrible state of affairs, especially when we realize
|> auto_ptr is the *only* smart pointer we have in the standard library.
|> In my opinion, it should be renamed to zombie_ptr if it is to keep its
|> new semantics.

It all depends what you want to use an auto_ptr for.  I have used classes
like this way before templates or exception handling were added to C++.
The main use was as insurance that certain resources were released on exit
from a block in the face of multiple exit paths from the block.

The January DWP continues to say that auto_ptr provides strict ownership
semantics [20.4.5  Template class auto_ptr]:

2 The auto_ptr provides a semantics of strict ownership.  An object  may
  be  safely  pointed  to  by  only one auto_ptr, so copying an auto_ptr
  copies the pointer and transfers ownership to the destination.

The implementation you have quoted does not contradict the above statement.
The January version of auto_ptr had the owner's stored pointer set to 0 so
that dereferencing under such conditions was not allowed:

X& operator*() const;

  Requires:
    get() != 0
  Returns:
    *get()

A simple amendment to the DWP, perhaps already in the works, is all we require:


X& operator*() const;

  Requires:
    owner == true
  Returns:
    *get()

With change, dereferencing will, as before, be undefined when ownership is 
not held.


-- 
John Hickin      Nortel Technology, Montreal, Quebec
(514) 765-7924   hickin@nortel.ca
---
[ comp.std.c++ is moderated.  To submit articles: try just posting with      ]
[ your news-reader.  If that fails, use mailto:std-c++@ncar.ucar.edu         ]
[ FAQ:      http://reality.sgi.com/employees/austern_mti/std-c++/faq.html    ]
[ Policy:   http://reality.sgi.com/employees/austern_mti/std-c++/policy.html ]
[ Comments? mailto:std-c++-request@ncar.ucar.edu                             ]