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.
diff --git a/Include/compile.h b/Include/compile.h
index f8acdb4..4d0da38 100644
--- a/Include/compile.h
+++ b/Include/compile.h
@@ -18,6 +18,8 @@
PyObject *co_consts; /* list (constants used) */
PyObject *co_names; /* list of strings (names used) */
PyObject *co_varnames; /* tuple of strings (local variable names) */
+ PyObject *co_freevars; /* tuple of strings (free variable names) */
+ PyObject *co_cellvars; /* tuple of strings (cell variable names) */
/* The rest doesn't count for hash/cmp */
PyObject *co_filename; /* string (where it was loaded from) */
PyObject *co_name; /* string (name, for reference) */
@@ -42,7 +44,8 @@
DL_IMPORT(PyCodeObject *) PyNode_Compile(struct _node *, char *);
DL_IMPORT(PyCodeObject *) PyCode_New(
int, int, int, int, PyObject *, PyObject *, PyObject *, PyObject *,
- PyObject *, PyObject *, int, PyObject *); /* same as struct above */
+ PyObject *, PyObject *, PyObject *, PyObject *, int, PyObject *);
+ /* same as struct above */
DL_IMPORT(int) PyCode_Addr2Line(PyCodeObject *, int);
/* for internal use only */
diff --git a/Include/frameobject.h b/Include/frameobject.h
index 1bbe2a1..c19f1d8 100644
--- a/Include/frameobject.h
+++ b/Include/frameobject.h
@@ -20,6 +20,7 @@
PyObject *f_builtins; /* builtin symbol table (PyDictObject) */
PyObject *f_globals; /* global symbol table (PyDictObject) */
PyObject *f_locals; /* local symbol table (PyDictObject) */
+ PyObject *f_closure; /* environment for free variables */
PyObject **f_valuestack; /* points after the last local */
PyObject *f_trace; /* Trace function */
PyObject *f_exc_type, *f_exc_value, *f_exc_traceback;
@@ -43,7 +44,8 @@
#define PyFrame_Check(op) ((op)->ob_type == &PyFrame_Type)
DL_IMPORT(PyFrameObject *) PyFrame_New(PyThreadState *, PyCodeObject *,
- PyObject *, PyObject *);
+ PyObject *, PyObject *,
+ PyObject *);
/* The rest of the interface is specific for frame objects */
diff --git a/Include/funcobject.h b/Include/funcobject.h
index 35ccf43..c8e97fd 100644
--- a/Include/funcobject.h
+++ b/Include/funcobject.h
@@ -12,6 +12,7 @@
PyObject *func_code;
PyObject *func_globals;
PyObject *func_defaults;
+ PyObject *func_closure;
PyObject *func_doc;
PyObject *func_name;
PyObject *func_dict;
@@ -26,6 +27,8 @@
extern DL_IMPORT(PyObject *) PyFunction_GetGlobals(PyObject *);
extern DL_IMPORT(PyObject *) PyFunction_GetDefaults(PyObject *);
extern DL_IMPORT(int) PyFunction_SetDefaults(PyObject *, PyObject *);
+extern DL_IMPORT(PyObject *) PyFunction_GetClosure(PyObject *);
+extern DL_IMPORT(int) PyFunction_SetClosure(PyObject *, PyObject *);
/* Macros for direct access to these values. Type checks are *not*
done, so use with care. */
@@ -35,6 +38,8 @@
(((PyFunctionObject *)func) -> func_globals)
#define PyFunction_GET_DEFAULTS(func) \
(((PyFunctionObject *)func) -> func_defaults)
+#define PyFunction_GET_CLOSURE(func) \
+ (((PyFunctionObject *)func) -> func_closure)
#ifdef __cplusplus
}
diff --git a/Include/opcode.h b/Include/opcode.h
index 0977585..89813ef 100644
--- a/Include/opcode.h
+++ b/Include/opcode.h
@@ -114,17 +114,17 @@
#define SET_LINENO 127 /* Current line number */
-/* It used to be the case that opcodes should fit in 7 bits. This is
- no longer the case -- 8 bits is fine (the instruction stream is now
- a sequence of unsigned characters). We gladly use the new space
- for new opcodes. */
-
#define RAISE_VARARGS 130 /* Number of raise arguments (1, 2 or 3) */
/* CALL_FUNCTION_XXX opcodes defined below depend on this definition */
#define CALL_FUNCTION 131 /* #args + (#kwargs<<8) */
#define MAKE_FUNCTION 132 /* #defaults */
#define BUILD_SLICE 133 /* Number of items */
+#define MAKE_CLOSURE 134 /* #free vars */
+#define LOAD_CLOSURE 135 /* Load free variable from closure */
+#define LOAD_DEREF 136 /* Load and dereference from closure cell */
+#define STORE_DEREF 137 /* Store into cell */
+
/* The next 3 opcodes must be contiguous and satisfy
(CALL_FUNCTION_VAR - CALL_FUNCTION) & 3 == 1 */
#define CALL_FUNCTION_VAR 140 /* #args + (#kwargs<<8) */