xo-interpreter: prep for xo-symboltable

README.md

@@ -1,3 +1,16 @@
-# xo-alloc -- arena allocator with rudimentary GC support
+# xo-alloc -- arena allocator and incremental garbage collector
 
-Xo-alloc is a lightweight arena allocator
+# Rules for writing garbage-collected classes.
+
+Topics
+* allocation  - allocate Objects (inheriting xo::Object) before owned scratch space.
+                 Can relax this if/when abandon the bad-for-locality use of two pointers
+                 into to-space to keep track of grey objects.  Want to use stack anyway
+                 so we can do depth-first search.
+* destructors - can omit except for finalization
+* assignment   - MUST USE Object::assign_member() to assign pointers to gc-owned memory.
+                 Only necessary for old->new pointers,  so don't need to worry about this
+                 for initialization.
+* finalization - not supported (yet)
+
+- padding - use IAlloc::with_padding(z) for hand-allocated objects.

include/xo/alloc/Object.hpp

@@ -191,8 +191,6 @@ namespace xo {
          **/
         virtual std::size_t _shallow_size() const = 0;
 
-         // TODO: _shallow_move() also overwrite *this with gc-only forwarding object point to C
-
         /** if subject is allocated by GC:
          *  - create copy C in to-space
          *  - destination C will be nursery|tenured depending on location of this.