gcc-in-cxx: Garbage Collecting STL Containers

[Basile STARYNKEVITCH]

Chris Jefferson wrote:
> Could someone point me towards what is necessary to add STL containers
> to the garbage collector?
> 
> One big problem with garbage collecting in C++ is the need to run
> destructors. If the (I believe very reasonable) decision is made to
> require that running destructors is not necessary for garbage
> collected types, then my experience is doing gc is very easy, and for
> garbage collection it's easy to just look at the internal members
> which all behave "sensibly".
> 
> Stripping away all the C++isms, and assuming that we use the default
> allocator which uses malloc, then a std::vector is just a struct
> 
> struct vector
> {
>   T* begin;
>   T* finish;
>   T* end_of_storage;
> };
> 
> Where we increment finish whenever we add something to the vector,
> until finish = end_of_storage, at which point new memory is allocated,
> the data is copied across, and then the old memory is freed. I can't
> think of any other (or any simpler) way to construct a variable sized
> container, in either C or C++.
> 
> Other containers are similar.

I fully agree on that point. To summarize: most of the classes in the 
gcc-in-cxx should have no destructor at all, or a trivial destructor 
which only destroys the data inside.

However, I am not sure this applies to std::string etc..

In addition, this raise several questions:

Does complex static data (i.e. statically allocated instances of complex 
classes) is allowed in gcc-in-cxx?

Do we intend to have a wide forest of classes in gcc-in-cxx? I would 
prefer a tree of classes (with only single inheritance) sharing a common 
root class.

At last, C++ permits interesting ways of writing garbage collectors, 
because it can help to make easier the boxing of GC-ed values on the stack.

Regards.

-- 
Basile STARYNKEVITCH         http://starynkevitch.net/Basile/
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