gras: formalize the weak container api w/ docs

address issue #69, we now have a set_container call,
which is now formally part of the api.

Anyone can call set_container for custom container types.
GRAS supports shared ptr and pyobject out of the box.

1 files changed, 1 insertions, 0 deletions

diff --git a/lib/element_impl.hpp b/lib/element_impl.hpp
index 869006e..3148d93 100644
--- a/lib/element_impl.hpp
+++ b/lib/element_impl.hpp
@@ -29,6 +29,7 @@ struct ElementImpl
     std::string name;
     long unique_id;
     std::string id;
+    boost::shared_ptr<WeakContainer> weak_self;
 
     //top block stuff
     SharedThreadGroup thread_group;