Resource HANDLES and the handling of such handles

[svenssonjoel]

Some times LBM programs may use things that are initialized and managed on the C side (arrays, drivers etc)
Handles are an encapsulation of a resource, It cannot be looked into or operated on by standard LBM, but it transfers knowledge between different extensions.

One idea is to add a HANDLE type to LBM that is just an integer (with some specific type bits). The lifetime of the handle is managed by the garbage collector (who calls a resource-manager-callback).

On the C side a resource handler needs to manage a datastructure (list or tree or whatever) of resources.
C gives to LBM a callback or set of callbacks (depending on direction one wants to take).

A specific resource handler is free to divide the set of handles into special and general-use handles.

Callbacks:

1. gc_handle_callback(handle);
2. can one imagine a resource initializer callback (that could be called in case a resource is needed but now yet initialized).
3. ...

The callbacks are the interface for LBM and extensions to interface with the HANDLE and its lifetime.

[svenssonjoel]

Think of a resource (on the C side) as a struct with these fields and potentially others more

id, payload-ptr, act-on-gc-fptr, init-fptr , ... , next

next encodes the list structure of resources.