"Larry Evans" <cppljevans@suddenlink.net> wrote in message news:g3gp99$9a2$1@ger.gmane.org... [...]
Hi Phil,
Even if you could find some way for your allocator to work for vector, I don't think it would work for other stl containers. These other containers, e.g. std::list<_Tp>, use Allocator<_Tp>::pointer to point to other elements in the container. AFAICT, what's needed for garbage collections is Allocator<_Tp>::root_pointer. This would be a *smart* pointer to the head of the list in the case of std::list<_Tp> and all other pointer would just be _Tp*. In the case of std::vector<_Tp>, I guess the start of the vector would be a *smart* pointer to _Tp[]. The iterators for a GC'ed vector would have to retain a copy of the root_pointer, I guess, in order to keep the whole vector alive if even 1 iterator were still around.
[...] Hey Larry how have you been doing? I moved to the South West and thus couldn't work on this for some years. But it sounds we violate [20.1.5/4] by doing so as stated by Kai-Uwe Bux: "Implementations of containers described in this International Standard are permitted to assume that their Allocator template parameter meets the following two additional requirements beyond those in Table 32. [...] ? The typedef members pointer, const_pointer, size_type, and difference_type are required to be T*,T const*, size_t, and ptrdiff_t, respectively." How strange is that because one might ask why these typedefs exists in the first place if we can't change them. Besides licensing I don't see why we couldn't cut & paste the whole STL and make these changes; I'll try that out tomorrow. [On the other hand STL should have explicit access to nodes but intrusive containers are already on their way and hopefully intrusive stacks too]
Anyway, I encountered a similar problem with the policy_ptr library I worked on years ago. The code used to be in the sandbox; hoever, I can't find it now. However, FWIW, there's this post:
http://article.gmane.org/gmane.comp.lib.boost.devel/155407/match=policy_ptr
Yeah there is a way to stack up the information I need by creating a separate list of pointers and will bypass all of this but creates messy code and I think STL changes is a better approach. -Phil