On Tuesday, July 1, 2003, at 08:21 PM, Schoenborn, Oliver wrote:
On Tuesday, Jul 1, 2003, at 17:36 America/Denver, Schoenborn, Oliver wrote:
On Tuesday, Jul 1, 2003, at 14:38 America/Denver, Boost wrote:
Why is there no strict-ownership smart-pointer in boost? Just curious to know what the reasons are. Thanks,
What do want beyond what boost::scoped_ptr and std::auto_ptr provide?
Ability to be used in STL containers, and explicit transfer of ownership capabilities (e.g. *no* move-on-copy etc).
So what would the copy semantics be?
No copy allowed, except temporarily when inside the container to insert or
re-order or transfer from one container to another.
Oliver
You may be looking for something that just doesn't exist in the language yet:
http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/papers/2002/ n1377.htm#move_ptr%20Example
This is a pointer with move semantics only, no copy semantics. And it does not move with copy syntax. Such a pointer is only a part of the solution. It also needs containers that know how to deal with a movable but non-copyable object. And of course language support makes everything click. :-\
I have experimented (actual working code) with what you're looking for. But the tools are *experimental* and not ready for prime time public use.
NTL ( http://www.ntllib.org/ ) claims to have this today (I think). I haven't looked at it closely enough to give a good review, but you might give it a go.
There's also:
http://pcroot.cern.ch/TaligentDocs/TaligentOnline/DocumentRoot/1.0/Docs/books/FS/FS_59.html
whose TInstanceOf or TOnlyPointerTo may be what your wanting.
Also, polaris ( http://polaris.cs.uiuc.edu ) had what it called Live and Ref Wrappers corresponding to Strong and Weak pointers; however, there could only be a single LiveWrapper to a heap allocated object. When that went away, the detructor was called; however, the memory was NOT reclaimed until all the RefWrapper's also went away. If a RefWrapper tried to access an object whose LiveWrapper had gone away, a run-time error was diagnosed. This was useful for things like program tree's where there could only be one owner (corresponding to the AST) but maybe several references to an owned object (e.g. a goto referencing another statement).
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