PEP 227 implementation

The majority of the changes are in the compiler.  The mainloop changes
primarily to implement the new opcodes and to pass a function's
closure to eval_code2().  Frames and functions got new slots to hold
the closure.

Include/compile.h
    Add co_freevars and co_cellvars slots to code objects.
    Update PyCode_New() to take freevars and cellvars as arguments
Include/funcobject.h
    Add func_closure slot to function objects.
    Add GetClosure()/SetClosure() functions (and corresponding
    macros) for getting at the closure.
Include/frameobject.h
    PyFrame_New() now takes a closure.
Include/opcode.h
    Add four new opcodes: MAKE_CLOSURE, LOAD_CLOSURE, LOAD_DEREF,
    STORE_DEREF.
    Remove comment about old requirement for opcodes to fit in 7
    bits.
compile.c
    Implement changes to code objects for co_freevars and co_cellvars.

    Modify symbol table to use st_cur_name (string object for the name
    of the current scope) and st_cur_children (list of nested blocks).
    Also define st_nested, which might more properly be called
    st_cur_nested.  Add several DEF_XXX flags to track def-use
    information for free variables.

    New or modified functions of note:
    com_make_closure(struct compiling *, PyCodeObject *)
        Emit LOAD_CLOSURE opcodes as needed to pass cells for free
        variables into nested scope.
    com_addop_varname(struct compiling *, int, char *)
        Emits opcodes for LOAD_DEREF and STORE_DEREF.
    get_ref_type(struct compiling *, char *name)
        Return NAME_CLOSURE if ref type is FREE or CELL
    symtable_load_symbols(struct compiling *)
        Decides what variables are cell or free based on def-use info.
        Can now raise SyntaxError if nested scopes are mixed with
        exec or from blah import *.
    make_scope_info(PyObject *, PyObject *, int, int)
        Helper functions for symtable scope stack.
    symtable_update_free_vars(struct symtable *)
        After a code block has been analyzed, it must check each of
        its children for free variables that are not defined in the
        block.  If a variable is free in a child and not defined in
        the parent, then it is defined by block the enclosing the
        current one or it is a global.  This does the right logic.
    symtable_add_use() is now a macro for symtable_add_def()
    symtable_assign(struct symtable *, node *)
        Use goto instead of for (;;)

    Fixed bug in symtable where name of keyword argument in function
    call was treated as assignment in the scope of the call site. Ex:
        def f():
            g(a=2) # a was considered a local of f

ceval.c
    eval_code2() now take one more argument, a closure.
    Implement LOAD_CLOSURE, LOAD_DEREF, STORE_DEREF, MAKE_CLOSURE>

    Also: When name error occurs for global variable, report that the
    name was global in the error mesage.

Objects/frameobject.c
    Initialize f_closure to be a tuple containing space for cellvars
    and freevars.  f_closure is NULL if neither are present.
Objects/funcobject.c
    Add support for func_closure.
Python/import.c
    Change the magic number.
Python/marshal.c
    Track changes to code objects.

1 files changed, 12 insertions, 3 deletions

diff --git a/Python/marshal.c b/Python/marshal.c
index 684a8b4c08..36d958abf8 100644
--- a/Python/marshal.c
+++ b/Python/marshal.c
@@ -238,6 +238,8 @@ w_object(PyObject *v, WFILE *p)
 		w_object(co->co_consts, p);
 		w_object(co->co_names, p);
 		w_object(co->co_varnames, p);
+		w_object(co->co_freevars, p);
+		w_object(co->co_cellvars, p);
 		w_object(co->co_filename, p);
 		w_object(co->co_name, p);
 		w_short(co->co_firstlineno, p);
@@ -554,6 +556,8 @@ r_object(RFILE *p)
 			PyObject *consts = NULL;
 			PyObject *names = NULL;
 			PyObject *varnames = NULL;
+			PyObject *freevars = NULL;
+			PyObject *cellvars = NULL;
 			PyObject *filename = NULL;
 			PyObject *name = NULL;
 			int firstlineno = 0;
@@ -563,7 +567,9 @@ r_object(RFILE *p)
 			if (code) consts = r_object(p);
 			if (consts) names = r_object(p);
 			if (names) varnames = r_object(p);
-			if (varnames) filename = r_object(p);
+			if (varnames) freevars = r_object(p);
+			if (freevars) cellvars = r_object(p);
+			if (cellvars) filename = r_object(p);
 			if (filename) name = r_object(p);
 			if (name) {
 				firstlineno = r_short(p);
@@ -572,9 +578,10 @@ r_object(RFILE *p)
 			
 			if (!PyErr_Occurred()) {
 				v = (PyObject *) PyCode_New(
-					argcount, nlocals, stacksize, flags, 
+					argcount, nlocals, stacksize, flags,  
 					code, consts, names, varnames,
-					filename, name, firstlineno, lnotab);
+					freevars, cellvars, filename, name, 
+					firstlineno, lnotab);  
 			}
 			else
 				v = NULL;
@@ -582,6 +589,8 @@ r_object(RFILE *p)
 			Py_XDECREF(consts);
 			Py_XDECREF(names);
 			Py_XDECREF(varnames);
+			Py_XDECREF(freevars);
+			Py_XDECREF(cellvars);
 			Py_XDECREF(filename);
 			Py_XDECREF(name);
 			Py_XDECREF(lnotab);