This is an elaboration on:
https://docs.python.org/2/library/dis.html
I copy the descriptions and add my notes, based on what I'm working on.
SETUP_LOOP(delta)
Pushes a block for a loop onto the block stack. The block spans from the current instruction with a size of delta bytes.
NOTES: compiler2 generates an extra SETUP_LOOP, for generator expressions, along with POP_BLOCK.
POP_BLOCK()
Removes one block from the block stack. Per frame, there is a stack of blocks, denoting nested loops, try statements, and such.
LOAD_CLOSURE(i)
Pushes a reference to the cell contained in slot i of the cell and free
variable storage. The name of the variable is co_cellvars[i] if i is less
than the length of co_cellvars. Otherwise it is
co_freevars[i - len(co_cellvars)].
NOTES: compiler2 generates an extra one of these
MAKE_CLOSURE(argc)
Creates a new function object, sets its func_closure slot, and pushes it on
the stack. TOS is the code associated with the function, TOS1 the tuple
containing cells for the closure’s free variables. The function also has argc
default parameters, which are found below the cells.
LOAD_DEREF(i)
Loads the cell contained in slot i of the cell and free variable storage.
Pushes a reference to the object the cell contains on the stack.
GET_ITER()
Implements TOS = iter(TOS).
NOTES: Hm how do I implement this? It turns it from a collection into an iterator. Gah.
PyObject *iter = PyObject_GetIter(iterable);
objects/abstract.c -
objects/iterobject.c - PySeqIter_New
PySeqIter_Type has a it_seq field. The PyObject being iterated over. It
maintains an index too.
How does items() work as an iterable then?
Then iter_iternext() calls:
PySequence_GetItem(seq, it->it_index)
LOAD_FAST(var_num)
Pushes a reference to the local co_varnames[var_num] onto the stack.
NOTES:
This still does a named lookup? Generator expressions do LOAD_FAST 0 (.0)
since there is no formal parameter name.
Oh I see, there is a PyObject** fastlocals in EvalFrame
It's initialized to f->f_localsplus -- frame holds them. Oh I see, that's
where the frame setup is different! Don't need inspect.callargs.
FastCall populates fastlocals from PyObject** args and nargs.