decode(): While writing tests for uu.py, Nick Mathewson discovered
that the 'Truncated input file' exception could never get raised,
because its "if not str:" test was actually testing the builtin
function "str", not the local string vrbl "s" as intended.
Bugfix candidate.
fixed. Regrettably, this must be run manually -- somehow the I/O
redirection of the regression test breaks the test. When run under
the regression test, this raises ImportError with a warning to that
effect.
Bugfix candidate!
Fix various serious problems:
- The ThreadingTCPServer class and its derived classes were completely
broken because the main thread would close the request before the
handler thread had time to look at it. This was introduced by
Ping's close_request() patch. The fix moves the close_request()
calls to after the handler has run to completion in the BaseServer
class and the ForkingMixIn class; when using the ThreadingMixIn,
closing the request is the handler's responsibility.
- The ForkingUDPServer class has always been been broken because the
socket was closed in the child before calling the handler. I fixed
this by simply not calling server_close() in the child at all.
- I cannot get the UnixDatagramServer class to work at all. The
recvfrom() call doesn't return a meaningful client address. I added
a comment to this effect. Maybe it works on other Unix versions.
- The __all__ variable was missing ThreadingMixIn and ForkingMixIn.
- Bumped __version__ to "0.4".
- Added a note about the test suite (to be checked in shortly).
solver. In conjunction, they easily found a tour of a 200x200 board:
that's 200**2 == 40,000 levels of backtracking. Explicitly resumable
generators allow that to be coded as easily as a recursive solver (easier,
actually, because different levels can use level-customized algorithms
without pain), but without blowing the stack. Indeed, I've never written
an exhaustive Tour solver in any language before that can handle boards so
large ("exhaustive" == guaranteed to find a solution if one exists, as
opposed to probabilistic heuristic approaches; of course, the age of the
universe may be a blip in the time needed!).
We should not depend on two spaces between words, so use the white
space after the to-be-encoded word only as lookahead and don't
actually consume it in the regular expression.
committed.
tokenize.py: I like these changes, and have tested them extensively
without even realizing it, so I just updated the docstring and the docs.
tabnanny.py: Also liked this, but did a little code fiddling. I should
really rewrite this to *exploit* generators, but that's near the bottom
of my effort/benefit scale so doubt I'll get to it anytime soon (it
would be most useful as a non-trivial example of ideal use of generators;
but test_generators.py has already grown plenty of food-for-thought
examples).
inspect.py: I'm sure Ping intended for this to continue running even
under 1.5.2, so I reverted this to the last pre-gen-branch version. The
"bugfix" I checked in in-between was actually repairing a bug *introduced*
by the conversion to generators, so it's OK that the reverted version
doesn't reflect that checkin.
class FieldStorage: this patch changes read_lines() and co. to use a
StringIO() instead of a real file. The write() calls are redirected
to a private method that replaces it with a real, external file only
when it gets too big (> 1000 bytes).
This avoids problems in forms using the multipart/form-data encoding
with many fields. The original code created a temporary file for
*every* field (not just for file upload fields), thereby sometimes
exceeding the open file limit of some systems.
Note that the simpler solution "use a real file only for file uploads"
can't be used because the form field parser has no way to tell which
fields correspond to file uploads.
It's *possible* but extremely unlikely that this would break someone's
code; they would have to be stepping way outside the documented
interface for FieldStorage and use f.file.fileno(), or depend on
overriding make_file() to return a file-like object with additional
known properties.
examples of use. These poke stuff not specifically targeted before, incl.
recursive local generators relying on nested scopes, ditto but also
inside class methods and rebinding instance vars, and anonymous
partially-evaluated generators (the N-Queens solver creates a different
column-generator for each row -- AFAIK this is my invention, and it's
really pretty <wink>). No problems, not even a new leak.
"return expr" instances in generators (which latter may be generators
due to otherwise invisible "yield" stmts hiding in "if 0" blocks).
This was fun the first time, but this has gotten truly ugly now.
that required explicitly calling LazyList.clear() in the two tests that
use LazyList (I added a LazyList Fibonacci generator too).
A real bitch: the extremely inefficient first version of the 2-3-5 test
*looked* like a slow leak on Win98SE, but it wasn't "really": it generated
so many results that the heap grew over 4Mb (tons of frames! the number
of frames grows exponentially in that test). Then Win98SE malloc() starts
fragmenting address space allocating more and more heaps, and the visible
memory use grew very slowly while the disk was thrashing like mad.
Printing fewer results (i.e., keeping the heap burden under 4Mb) made
that illusion vanish.
Looks like there's no hope for plugging the LazyList leaks automatically
short of adding frameobjects and genobjects to gc. OTOH, they're very
easy to break by hand, and they're the only *kind* of plausibly realistic
leaks I've been able to provoke.
Dilemma.
Implement sys.maxunicode.
Explicitly wrap around upper/lower computations for wide Py_UNICODE.
When decoding large characters with UTF-8, represent expected test
results using the \U notation.
break cycles, which are a special problem when running generator tests
that provoke exceptions by invoking the .next() method of a named
generator-iterator: then the iterator is named in globs, and the
iterator's frame gets a tracekback object pointing back to globs, and
gc doesn't chase these types so the cycle leaks.
Also changed _run_examples() to make a copy of globs itself, so its
callers (direct and indirect) don't have to (and changed the callers
to stop making their own copies); *that* much is a change I've been
meaning to make for a long time (it's more robust the new way).
Here's a way to provoke the symptom without doctest; it leaks at a
prodigious rate; if the last two "source" lines are replaced with
g().next()
the iterator isn't named and then there's no leak:
source = """\
def g():
yield 1/0
k = g()
k.next()
"""
code = compile(source, "<source>", "exec")
def f(globs):
try:
exec code in globs
except ZeroDivisionError:
pass
while 1:
f(globals().copy())
After this change, running test_generators in an infinite loop still leaks,
but reduced from a flood to a trickle.
Good news: Some of this stuff is pretty sophisticated (read nuts), and
I haven't bumped into a bug yet.
Bad news: If I run the doctest in an infinite loop, memory is clearly
leaking.
- compile() didn't return a (empty) list of objects. Fixed.
- the various _fix_xxx_args() methods weren't called (are they new or did I overlook them?). Fixed.
write a BOM at the start of the stream and also to only read it as
BOM at the start of a stream.
Subsequent reading/writing of BOMs will read/write the BOM as ZWNBSP
character. This is in sync with the Unicode specifications.
Note that UTF-16 files will now *have* to start with a BOM mark
in order to be readable by the codec.
addition of interface for consistency with base64 module. Namely,
encodestring(), decodestring(): New functions which accept a string
object and return a string object. They just wrap the string in
StringIOs and pass them to the encode() and decode() methods
respectively. encodestring() accepts a default argument of quotetabs,
defaulting to zero, which is passed on straight through to encode().
encode(): Fix the bug where an extra newline would always be added to
the output, which prevented an idempotent roundtrip through
encode->decode. Now, if the source string doesn't end in a newline,
then the result string won't end in a newline.
Also, extend the quotetabs argument semantics to include quoting
embedded strings, which is also optional according to the RFC.
test() -> main()
"from quopri import *" also imports encodestring() and decodestring().
i_divmod: New and simpler algorithm. Old one returned gibberish on most
boxes when the numerator was -sys.maxint-1. Oddly enough, it worked in the
release (not debug) build on Windows, because the compiler optimized away
some tricky sign manipulations that were incorrect in this case.
Makes you wonder <wink> ...
Bugfix candidate.
Summary: NAMESPACE support in imaplib.py
Initial Comment:
Support for the IMAP NAMESPACE extension defined in rfc
2342. This is almost a necessity for working with
modern IMAP servers.
Unfortunately, the std-mode bBhHIL codes don't do any range-checking; if
and when some of those get fixed, remove their letters from the
IntTester.BUGGY_RANGE_CHECK string. In the meantime, a msg saying that
range-tests are getting skipped is printed to stdout whenever one is
skipped.
This completes the q/Q project.
longobject.c _PyLong_AsByteArray: The original code had a gross bug:
the most-significant Python digit doesn't necessarily have SHIFT
significant bits, and you really need to count how many copies of the sign
bit it has else spurious overflow errors result.
test_struct.py: This now does exhaustive std q/Q testing at, and on both
sides of, all relevant power-of-2 boundaries, both positive and negative.
NEWS: Added brief dict news while I was at it.
native mode, and only when config #defines HAVE_LONG_LONG. Standard mode
will eventually treat them as 8-byte ints across all platforms, but that
likely requires a new set of routines in longobject.c first (while
sizeof(long) >= 4 is guaranteed by C, there's nothing in C we can rely
on x-platform to hold 8 bytes of int, so we'll have to roll our own;
I'm thinking of a simple pair of conversion functions, Python long
to/from sized vector of unsigned bytes; that may be useful for GMP
conversions too; std q/Q would call them with size fixed at 8).
test_struct.py: In addition to adding some native-mode 'q' and 'Q' tests,
got rid of unused code, and repaired a non-portable assumption about
native sizeof(short) (it isn't 2 on some Cray boxes).
libstruct.tex: In addition to adding a bit of 'q'/'Q' docs (more needed
later), removed an erroneous footnote about 'I' behavior.
Patch from Michael Hundson.
format_exception_only() blew up when trying to report a SyntaxError
from a string input (line is None in this case, but it assumed a string).
Bugfix candidate.
Armin Rigo pointed out that the way the line-# table got built didn't work
for lines generating more than 255 bytes of bytecode. Fixed as he
suggested, plus corresponding changes to pyassem.py, plus added some
long overdue docs about this subtle table to compile.c.
Bugfix candidate (line numbers may be off in tracebacks under -O).
case of objects with equal types which support tp_compare. Give
type objects a tp_compare function.
Also add c<0 tests before a few PyErr_Occurred tests.
Ensure that all the default timers are called as functions, not an
expensive method wrapper around a variety of different functions.
Agressively avoid dictionary lookups.
Modify the dispatch scheme (Profile.trace_dispatch_*(), where * is not
'call', 'exception' or 'return') so that the callables dispatched to
are simple functions and not bound methods -- this reduces the number
of layers of Python call machinery that gets touched.
Remove a couple of duplicate imports from the "if __name__ == ..."
section.
This closes SF patch #430948.
be possible to provoke unbounded recursion now, but leaving that to someone
else to provoke and repair.
Bugfix candidate -- although this is getting harder to backstitch, and the
cases it's protecting against are mondo contrived.
random inputs: if you ran the test 100 times, you could expect it to
report a bogus failure. So loosened its expectations.
Also changed the way failing tests are printed, so that when run under
regrtest.py we get enough info to reproduce the failure.
exactly once. But the test code can't know that, as the number of times
__cmp__ is called depends on internal details of the dict implementation.
This is especially nasty because the __hash__ method returns the address
of the class object, so the hash codes seen by the dict can vary across
runs, causing the dict to use a different probe order across runs. I
just happened to see this test fail about 1 run in 7 today, but only
under a release build and when passing -O to Python. So, changed the test
to be predictable across runs.
name of the test, only write the output file if it already exists (and
tell the user to consider removing it). This avoids the generation of
unnecessary turds.
updatecache(): When using imputil, sys.path may contain things other than
strings. Ignore such things instead of blowing up.
Hard to say whether this is a bugfix or a feature ...
dictresize() was too aggressive about never ever resizing small dicts.
If a small dict is entirely full, it needs to rebuild it despite that
it won't actually resize it, in order to purge old dummy entries thus
creating at least one virgin slot (lookdict assumes at least one such
exists).
Also took the opportunity to add some high-level comments to dictresize.
setdefault() the empty string. In setdefault(), use + to join the value
to create the entry for the headers attribute so that TypeError is raised
if the value is of the wrong type.
When regrtest.py finds an attribute "test_main" in a test it imports,
regrtest runs the test's test_main after the import. test_threaded_import
needs this else the cross-thread import lock prevents it from making
progress. Other tests can use this hack too, but I doubt it will ever be
popular.
ICK ALERT: read the long comment block before run_the_test(). It was
almost impossible to get this to run without instant deadlock, and the
solution here sucks on several counts. If you can dream up a better way,
let me know!
basically accept <!...> where the dots can be single- or double-quoted
strings or any other character except >.
Background: I found a real-life example that failed to parse with
the old assumption: http://www.opensource.org/licenses/jabberpl.html
contains a few constructs of the form <![if !supportLists]>...<![endif]>.
derived from but not quite compatible with that of sgmllib, so it's a
new file. I suppose it needs documentation, and htmllib needs to be
changed to use this instead of sgmllib, and sgmllib needs to be
declared obsolete. But that can all be done later.
This code was first published as part of TAL (part of Zope Page
Templates), but that was strongly based on sgmllib anyway. Authors
are Fred drake and Guido van Rossum.
codec files to codecs.py and added logic so that multi mappings
in the decoding maps now result in mappings to None (undefined mapping)
in the encoding maps.
and introduces a new method .decode().
The major change is that strg.encode() will no longer try to convert
Unicode returns from the codec into a string, but instead pass along
the Unicode object as-is. The same is now true for all other codec
return types. The underlying C APIs were changed accordingly.
Note that even though this does have the potential of breaking
existing code, the chances are low since conversion from Unicode
previously took place using the default encoding which is normally
set to ASCII rendering this auto-conversion mechanism useless for
most Unicode encodings.
The good news is that you can now use .encode() and .decode() with
much greater ease and that the door was opened for better accessibility
of the builtin codecs.
As demonstration of the new feature, the patch includes a few new
codecs which allow string to string encoding and decoding (rot13,
hex, zip, uu, base64).
Written by Marc-Andre Lemburg. Copyright assigned to the PSF.
*are* obsolete; three variables and the maketrans() function are not
(yet) obsolete.
Add a compensating warnings.filterwarnings() call to test_strop.py.
Add this to the NEWS.
elements when crunching a list, dict or tuple. Now takes linear time
instead -- huge speedup for even moderately large containers, and the
code is notably simpler too.
Added some basic "is the output correct?" tests to test_pprint.
The comment following used to say:
/* We use ~hash instead of hash, as degenerate hash functions, such
as for ints <sigh>, can have lots of leading zeros. It's not
really a performance risk, but better safe than sorry.
12-Dec-00 tim: so ~hash produces lots of leading ones instead --
what's the gain? */
That is, there was never a good reason for doing it. And to the contrary,
as explained on Python-Dev last December, it tended to make the *sum*
(i + incr) & mask (which is the first table index examined in case of
collison) the same "too often" across distinct hashes.
Changing to the simpler "i = hash & mask" reduced the number of string-dict
collisions (== # number of times we go around the lookup for-loop) from about
6 million to 5 million during a full run of the test suite (these are
approximate because the test suite does some random stuff from run to run).
The number of collisions in non-string dicts also decreased, but not as
dramatically.
Note that this may, for a given dict, change the order (wrt previous
releases) of entries exposed by .keys(), .values() and .items(). A number
of std tests suffered bogus failures as a result. For dicts keyed by
small ints, or (less so) by characters, the order is much more likely to be
in increasing order of key now; e.g.,
>>> d = {}
>>> for i in range(10):
... d[i] = i
...
>>> d
{0: 0, 1: 1, 2: 2, 3: 3, 4: 4, 5: 5, 6: 6, 7: 7, 8: 8, 9: 9}
>>>
Unfortunately. people may latch on to that in small examples and draw a
bogus conclusion.
test_support.py
Moved test_extcall's sortdict() into test_support, made it stronger,
and imported sortdict into other std tests that needed it.
test_unicode.py
Excluced cp875 from the "roundtrip over range(128)" test, because
cp875 doesn't have a well-defined inverse for unicode("?", "cp875").
See Python-Dev for excruciating details.
Cookie.py
Chaged various output functions to sort dicts before building
strings from them.
test_extcall
Fiddled the expected-result file. This remains sensitive to native
dict ordering, because, e.g., if there are multiple errors in a
keyword-arg dict (and test_extcall sets up many cases like that), the
specific error Python complains about first depends on native dict
ordering.
A Mystery: test_mutants ran amazingly slowly even before dictobject.c
"got fixed". I don't have a clue as to why. dict comparison was and
remains linear-time in the size of the dicts, and test_mutants only tries
100 dict pairs, of size averaging just 50. So "it should" run in less than
an eyeblink; but it takes at least a second on this 800MHz box.
Fixed a half dozen ways in which general dict comparison could crash
Python (even cause Win98SE to reboot) in the presence of kay and/or
value comparison routines that mutate the dict during dict comparison.
Bugfix candidate.
meaning infinity -- but at least warn about it in the code! I pissed
away a couple hours on this today, and don't wish the same on the next
in line.
Bugfix candidate.
means "replace everything". But the string module, string.replace()
amd test_string.py believe a 0 count means "replace nothing".
"Nothing" wins, strop loses.
Bugfix candidate.
Platform blew up on "123".replace("123", ""). Michael Hudson pinned the
blame on platform malloc(0) returning NULL.
This is a candidate for all bugfix releases.
Store floats and doubles to full precision in marshal.
Test that floats read from .pyc/.pyo closely match those read from .py.
Declare PyFloat_AsString() in floatobject header file.
Add new PyFloat_AsReprString() API function.
Document the functions declared in floatobject.h.
d1 == d2 and d1 != d2 now work even if the keys and values in d1 and d2
don't support comparisons other than ==, and testing dicts for equality
is faster now (especially when inequality obtains).
another change (to test_import.py, which simply imports the new file). I'm
checking this piece in now, though, to make it easier to distribute a patch
for x-platform checking.
NEEDS DOC CHANGES.
More AttributeErrors transmuted into TypeErrors, in test_b2.py, and,
again, this strikes me as a good thing.
This checkin completes the iterator generalization work that obviously
needed to be done. Can anyone think of others that should be changed?
safely together and don't duplicate logic (the common logic was factored
out into new private API function _PySequence_IterContains()).
Visible change:
some_complex_number in some_instance
no longer blows up if some_instance has __getitem__ but neither
__contains__ nor __iter__. test_iter changed to ensure that remains true.
NEEDS DOC CHANGES
A few more AttributeErrors turned into TypeErrors, but in test_contains
this time.
The full story for instance objects is pretty much unexplainable, because
instance_contains() tries its own flavor of iteration-based containment
testing first, and PySequence_Contains doesn't get a chance at it unless
instance_contains() blows up. A consequence is that
some_complex_number in some_instance
dies with a TypeError unless some_instance.__class__ defines __iter__ but
does not define __getitem__.
to string.join(), so that when the latter figures out in midstream that
it really needs unicode.join() instead, unicode.join() can actually get
all the sequence elements (i.e., there's no guarantee that the sequence
passed to string.join() can be iterated over *again* by unicode.join(),
so string.join() must not pass on the original sequence object anymore).
NEEDS DOC CHANGES.
This one surprised me! While I expected tuple() to be a no-brainer, turns
out it's actually dripping with consequences:
1. It will *allow* the popular PySequence_Fast() to work with any iterable
object (code for that not yet checked in, but should be trivial).
2. It caused two std tests to fail. This because some places used
PyTuple_Sequence() (the C spelling of tuple()) as an indirect way to test
whether something *is* a sequence. But tuple() code only looked for the
existence of sq->item to determine that, and e.g. an instance passed
that test whether or not it supported the other operations tuple()
needed (e.g., __len__). So some things the tests *expected* to fail
with an AttributeError now fail with a TypeError instead. This looks
like an improvement to me; e.g., test_coercion used to produce 559
TypeErrors and 2 AttributeErrors, and now they're all TypeErrors. The
error details are more informative too, because the places calling this
were *looking* for TypeErrors in order to replace the generic tuple()
"not a sequence" msg with their own more specific text, and
AttributeErrors snuck by that.
NEEDS DOC CHANGES.
Possibly contentious: The first time s.next() yields StopIteration (for
a given map argument s) is the last time map() *tries* s.next(). That
is, if other sequence args are longer, s will never again contribute
anything but None values to the result, even if trying s.next() again
could yield another result. This is the same behavior map() used to have
wrt IndexError, so it's the only way to be wholly backward-compatible.
I'm not a fan of letting StopIteration mean "try again later" anyway.
to no longer insist that len(seq) be defined.
NEEDS DOC CHANGES.
This is meant to be a model for how other functions of this ilk (max,
filter, etc) can be generalized similarly. Feel encouraged to grab your
favorite and convert it!
Note some cute consequences:
list(file) == file.readlines() == list(file.xreadlines())
list(dict) == dict.keys()
list(dict.iteritems()) = dict.items()
list(xrange(i, j, k)) == range(i, j, k)
The new test case demonstrates the bug. Be more careful in
symtable_resolve_free() to add a var to cells or frees only if it
won't be added under some other rule.
XXX Add new assertion that will catch this bug.
of ParserCreate().
Added assignment tests for the ordered_attributes and specified_attributes
values, similar to the checks for the returns_unicode attribute.
Obviously bad regexps, spotted by Jeffery Collins.
HELP! I can't run this on Windows, and the module test() function
probably doesn't work on anyone's box. Could a Unixoid please write
an at least minimal working test and add it to the std test suite?
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???)
I know some people don't like this -- if it's really controversial,
I'll take it out again. (If it's only Alex Martelli who doesn't like
it, that doesn't count as "real controversial" though. :-)
That's why this is a separate checkin from the iterators stuff I'm
about to check in next.
Weak*Dictionary.update(): No longer create a temporary list to hold the
things that will be stuffed into the underlying dictionary. This had
been done so that if any of the objects used as the weakly-held value
was not weakly-referencable, no updates would take place (TypeError
would be raised). With this change, TypeError will still be raised
but a partial update could occur. This is more like other .update()
implementations.
Thoughout, use of the name "ref" as a local variable has been removed. The
original use of the name occurred when the function to create a weak
reference was called "new"; the overloaded use of the name could be
confusing for someone reading the code. "ref" used as a variable name
has been replaced with "wr" (for 'weak reference').
The changes cause compilation failures in any file in the Python
installation lib directory to cause the install to fail. It looks
like compileall.py intended to behave this way, but a change to
py_compile.py and a separate bug defeated it.
Fixes SF bug #412436
This change affects the test suite, which contains several files that
contain intentional errors. The solution is to extend compileall.py
with the ability to skip compilation of selected files.
NB compileall.py is changed so that compile_dir() returns success only
if all recursive calls to compile_dir() also check success.
The changes cause compilation failures in any file in the Python
installation lib directory to cause the install to fail. It looks
like compileall.py intended to behave this way, but a change to
py_compile.py and a separate bug defeated it.
Fixes SF bug #412436
This change affects the test suite, which contains several files that
contain intentional errors. The solution is to extend compileall.py
with the ability to skip compilation of selected files.
In the test suite, rename nocaret.py and test_future[3..7].py to start
with badsyntax_nocaret.py and badsyntax_future[3..7].py. Update the
makefile to skip compilation of these files. Update the tests to use
the name names for imports.
NB compileall.py is changed so that compile_dir() returns success only
if all recursive calls to compile_dir() also check success.
file was deleted by a previous call to the visitor function.
This used to be the behavior in 1.5.2 and before, but a patch to avoid
making two stat() calls accidentally broke this in 2.0.
Moshe, this would be a good one for 2.0.1 too!
its first return statement returns a single value while its caller
always expects it to return a tuple of two items. Fix this by
returning (s, 0) instead.
This won't make the locale test on Irix succeed, but now it will fail
because of a bug in the platform's en_US locale rather than because of
a bug in the locale module.
than from module pickletester. Using the latter turned out to cause
the test to break when invoked as "import test.test_pickle" or "import
test.autotest".
cut-and-paste copy of the seek() method on the _Subfile class, but it
didn't make one bit of sense: it sets self.pos, which is not used in
this class or its subclasses, and it uses self.start and self.stop,
which aren't defined on this class or its subclasses. This is purely
my own fault -- I added this in rev 1.4 and apparently never tried to
use it. Since it's not documented, and of very questionable use given
that there's no tell(), I'm ripping it out.
This resolves SF bug 416199 by Andrew Dalke: mailbox.py seek problems.
ZipFile.close() method that should be part of the preceding 'if'
block. On some platforms (Mark noticed this on FreeBSD 4.2) doing a
flush() on a file open for reading is not allowed.
now raises NameError instead of UnboundLocalError, because the var in
question is definitely not local. (This affects test_scope.py)
Also update the recent fix by Ping using get_func_name(). Replace
tests of get_func_name() return value with call to get_func_desc() to
match all the other uses.