use wrappers on all platforms, to make this as consistent as possible x-
platform (in particular, make sure there's at least one \0 byte in
the output buffer). Also document more of the truth about what these do.
getargs.c, seterror(): Three computations of remaining buffer size were
backwards, thus telling PyOS_snprintf the buffer is larger than it
actually is. This matters a lot now that PyOS_snprintf ensures there's a
trailing \0 byte (because it didn't get the truth about the buffer size,
it was storing \0 beyond the true end of the buffer).
sysmodule.c, mywrite(): Simplify, now that PyOS_vsnprintf guarantees to
produce a \0 byte.
Python warning which can be catched by means of the Python warning
framework.
It also adds two new APIs which hopefully make it easier for Python
to switch to buffer overflow safe [v]snprintf() APIs for error
reporting et al. The two new APIs are PyOS_snprintf() and
PyOS_vsnprintf() and work just like the standard ones in many
C libs. On platforms which have snprintf(), the native APIs are used,
on all other an emulation with snprintf() tries to do its best.
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???)
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().
Introduce a new builtin exception, UnboundLocalError, raised when ceval.c
tries to retrieve or delete a local name that isn't bound to a value.
Currently raises NameError, which makes this behavior a FAQ since the same
error is raised for "missing" global names too: when the user has a global
of the same name as the unbound local, NameError makes no sense to them.
Even in the absence of shadowing, knowing whether a bogus name is local or
global is a real aid to quick understanding.
Example:
D:\src\PCbuild>type local.py
x = 42
def f():
print x
x = 13
return x
f()
D:\src\PCbuild>python local.py
Traceback (innermost last):
File "local.py", line 8, in ?
f()
File "local.py", line 4, in f
print x
UnboundLocalError: x
D:\src\PCbuild>
Note that UnboundLocalError is a subclass of NameError, for compatibility
with existing class-exception code that may be trying to catch this as a
NameError. Unfortunately, I see no way to make this wholly compatible
with -X (see comments in bltinmodule.c): under -X, [UnboundLocalError
is an alias for NameError --GvR].
[The ceval.c patch differs slightly from the second version that Tim
submitted; I decided not to raise UnboundLocalError for DELETE_NAME,
only for DELETE_LOCAL. DELETE_NAME is only generated at the module
level, and since at that level a NameError is raised for referencing
an undefined name, it should also be raised for deleting one.]
