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Peter Dimov
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 Posted: Tue Aug 17, 2004 11:43 pm Post subject: Re: Marking pointer ownership semantics |
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[email]cdiggins (AT) videotron (DOT) ca[/email] ("christopher diggins") wrote in message news:<kZ9Uc.56580$sk2.829133 (AT) wagner (DOT) videotron.net>...
| Quote: | In my programming language Heron, I have mark pointer ownership semantics
using an extra symbol. It occured to me that this might be something worthy
of consideration for C++.
The motivation is essentially this, when a function acts as an object
factory we rely on a naming convention or other form of documentation to
indicate to the user of that function that the responsibility for deletion
of the object is being tranfserred to the owner.
Consider the following example:
AbstractIterator* SomeCollectionClass::CreateRunTimeIterator() {
return new AppropriateConcreteIterator;
}
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This function is flawed, since it returns an unmanaged resource. It
should return auto_ptr, shared_ptr, or another smart pointer or
handle, as appropriate.
[...]
| Quote: | We could in C++ introduce a special kind of pointer, say MyObject^ which was
distinguishable from MyObject* in that it could only be initialized or
assigned from anything but another owner pointer or the results of a new
operation.
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There is a certain appeal to new returning a special kind of pointer.
However if we could change the return type of new X (we can't, really,
it will break too much existing code), what's wrong with auto_ptr<X>?
You ask some interesting questions in The Joel on Software forum. Too
bad I don't read it.  Without going too off-topic (this is c.s.c++
after all):
http://boost.org/libs/smart_ptr/sp_techniques.html#weak_without_shared
may give you some ideas about weak pointers to stack objects.
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