Re: [boost] portable precise garbage collector for C++

From: Larry Evans (cppljevans_at_[hidden])
Date: 2007-09-23 14:47:04

On 09/23/07 13:31, Achilleas Margaritis wrote:
> O/H Larry Evans έγραψε:
[snip]
>> The main_stl.zip in boost-vault/memory uses Sebastian's suggestion and
>> it seems to work.  It runs a little std_list test, then a GCBench
>> with std:pair, then GCBench with std_list<., gc_allocator>.
>>
>> As (I think) you're pointing out above, the std_list<T,gc_allocator<T> >
>> would define gc_allocator<T>::pointer as gc_ptr<T>, which is
>> never used in std_list at all because the std_list stores the
>> complete T (not T*) in std_list<...>::node.  I can see where this
>> would be confusing and is a shortcoming of the allocator model.
>> It just happens to work in this case.
> 
> I am not really following you. Does your STL list class use the class 
> gc_allocator<T> or not? and if it does, does it use it fully for all its 
> operations or for some of them?

It can, just like std::list can.  IOW, it can be the 2nd template
parameter.  The list_pair template (derived from std_list) uses
gc_allocator as the 2nd template parameter of its superclass,
std_list<Node,gc_allocator<Node> >.

It doesn't use it for any operations because
it's part of the nested  std::list<.,.>::node used to implement the
list.  Only push_back was coded since that's the only one used.
I guess the std_list::empty is not standard; however, that's
not really important since the only purpose was to demonstrate
how, possibly a future std::list, could be coded to allow
your gc_allocator to be used.  Now that I think about it,
maybe only the std_list::node::_next needs to be a gc_ptr<.>.
That would save some time.