new slot tp_iter in type object, plus new flag Py_TPFLAGS_HAVE_ITER
new C API PyObject_GetIter(), calls tp_iter
new builtin iter(), with two forms: iter(obj), and iter(function, sentinel)
new internal object types iterobject and calliterobject
new exception StopIteration
new opcodes for "for" loops, GET_ITER and FOR_ITER (also supported by dis.py)
new magic number for .pyc files
new special method for instances: __iter__() returns an iterator
iteration over dictionaries: "for x in dict" iterates over the keys
iteration over files: "for x in file" iterates over lines
TODO:
documentation
test suite
decide whether to use a different way to spell iter(function, sentinal)
decide whether "for key in dict" is a good idea
use iterators in map/filter/reduce, min/max, and elsewhere (in/not in?)
speed tuning (make next() a slot tp_next???)
Update docstring and library reference section on 'sys' module.
New API PyErr_Display, just for displaying errors, called by excepthook.
Uncaught exceptions now call sys.excepthook; if that fails, we fall back
to calling PyErr_Display directly.
Also comes with sys.__excepthook__ and sys.__displayhook__.
must now initialize the extra field used by the weak-ref machinery to
NULL themselves, to avoid having to require PyObject_INIT() to check
if the type supports weak references and do it there. This causes less
work to be done for all objects (the type object does not need to be
consulted to check for the Py_TPFLAGS_HAVE_WEAKREFS bit).
If a module has a future statement enabling nested scopes, they are
also enable for the exec statement and the functions compile() and
execfile() if they occur in the module.
If Python is run with the -i option, which enters interactive mode
after executing a script, and the script it runs enables nested
scopes, they are also enabled in interactive mode.
XXX The use of -i with -c "from __future__ import nested_scopes" is
not supported. What's the point?
To support these changes, many function variants have been added to
pythonrun.c. All the variants names end with Flags and they take an
extra PyCompilerFlags * argument. It is possible that this complexity
will be eliminated in a future version of the interpreter in which
nested scopes are not optional.
with free variables. Thanks to Martin v. Loewis for finding two of
the problems. This fixes SF buf 405583.
There is also a C API change: PyFrame_New() is reverting to its
pre-2.1 signature. The change introduced by nested scopes was a
mistake. XXX Is this okay between beta releases?
cell_clear(), the GC helper, must decref its reference to break
cycles.
frame_dealloc() must dealloc all cell vars and free vars in addition
to locals.
eval_code2() setup code must INCREF cells it copies out of the
closure.
The STORE_DEREF opcode implementation must DECREF the object it passes
to PyCell_Set().
(Also remove warning about module-level global decl, because we can't
distinguish from code passed to exec.)
Define PyCompilerFlags type contains a single element,
cf_nested_scopes, that is true if a nested scopes future statement has
been entered at the interactive prompt.
New API functions:
PyNode_CompileFlags()
PyRun_InteractiveOneFlags()
-- same as their non Flags counterparts except that the take an
optional PyCompilerFlags pointer
compile.c: In jcompile() use PyCompilerFlags argument. If
cf_nested_scopes is true, compile code with nested scopes. If it
is false, but the code has a valid future nested scopes statement,
set it to true.
pythonrun.c: Create a new PyCompilerFlags object in
PyRun_InteractiveLoop() and thread it through to
PyRun_InteractiveOneFlags().
for errors raised in future.c.
Move some helper functions from compile.c to errors.c and make them
API functions: PyErr_SyntaxLocation() and PyErr_ProgramText().
XXX still need to integrate into symtable API
compile.h: Remove ff_n_simple_stmt; obsolete.
Add ff_found_docstring used internally to skip one and only
one string at the beginning of a module.
compile.c: Add check for from __future__ imports to far into the file.
In symtable_global() check for -1 returned from
symtable_lookup(), which signifies name not defined.
Add missing DECERF in symtable_add_def.
Free c->c_future.
future.c: Add special handling for multiple statements joined on a
single line using one or more semicolons; this form can
include an illegal future statement that would otherwise be
hard to detect.
Add support for detecting and skipping doc strings.
Makefile.pre.in: add target future.o
Include/compile.h: define PyFutureFeaters and PyNode_Future()
add c_future slot to struct compiling
Include/symtable.h: add st_future slot to struct symtable
Python/future.c: implementation of PyNode_Future()
Python/compile.c: use PyNode_Future() for nested_scopes support
Python/symtable.c: include compile.h to pick up PyFutureFeatures decl
compile.h: #define NESTED_SCOPES_DEFAULT 0 for Python 2.1
__future__ feature name: "nested_scopes"
symtable.h: Add st_nested_scopes slot. Define flags to track exec and
import star.
Lib/test/test_scope.py: requires nested scopes
compile.c: Fiddle with error messages.
Reverse the sense of ste_optimized flag on
PySymtableEntryObjects. If it is true, there is an optimization
conflict.
Modify get_ref_type to respect st_nested_scopes flags.
Refactor symtable_load_symbols() into several smaller functions,
which use struct symbol_info to share variables. In new function
symtable_update_flags(), raise an error or warning for import * or
bare exec that conflicts with nested scopes. Also, modify handle
for free variables to respect st_nested_scopes flag.
In symtable_init() assign st_nested_scopes flag to
NESTED_SCOPES_DEFAULT (defined in compile.h).
Add preliminary and often incorrect implementation of
symtable_check_future().
Add symtable_lookup() helper for future use.
