Anyway, this is the changes to the with-statement
so that __exit__ must return a true value in order
for a pending exception to be ignored.
The PEP (343) is already updated.
added message attribute compared to the previous version of Exception. It is
also a new-style class, making all exceptions now new-style. KeyboardInterrupt
and SystemExit inherit from BaseException directly. String exceptions now
raise DeprecationWarning.
Applies patch 1104669, and closes bugs 1012952 and 518846.
- New semantics for __exit__() -- it must re-raise the exception
if type is not None; the with-statement itself doesn't do this.
(See the updated PEP for motivation.)
- Added context managers to:
- file
- thread.LockType
- threading.{Lock,RLock,Condition,Semaphore,BoundedSemaphore}
- decimal.Context
- Added contextlib.py, which defines @contextmanager, nested(), closing().
- Unit tests all around; bot no docs yet.
- IMPORT_NAME takes an extra argument from the stack: the relativeness of
the import. Only passed to __import__ when it's not -1.
- __import__() takes an optional 5th argument for the same thing; it
__defaults to -1 (old semantics: try relative, then absolute)
- 'from . import name' imports name (be it module or regular attribute)
from the current module's *package*. Likewise, 'from .module import name'
will import name from a sibling to the current module.
- Importing from outside a package is not allowed; 'from . import sys' in a
toplevel module will not work, nor will 'from .. import sys' in a
(single-level) package.
- 'from __future__ import absolute_import' will turn on the new semantics
for import and from-import: imports will be absolute, except for
from-import with dots.
Includes tests for regular imports and importhooks, parser changes and a
NEWS item, but no compiler-package changes or documentation changes.
This was started by Mike Bland and completed by Guido
(with help from Neal).
This still needs a __future__ statement added;
Thomas is working on Michael's patch for that aspect.
There's a small amount of code cleanup and refactoring
in ast.c, compile.c and ceval.c (I fixed the lltrace
behavior when EXT_POP is used -- however I had to make
lltrace a static global).
In C++, it's an error to pass a string literal to a char* function
without a const_cast(). Rather than require every C++ extension
module to put a cast around string literals, fix the API to state the
const-ness.
I focused on parts of the API where people usually pass literals:
PyArg_ParseTuple() and friends, Py_BuildValue(), PyMethodDef, the type
slots, etc. Predictably, there were a large set of functions that
needed to be fixed as a result of these changes. The most pervasive
change was to make the keyword args list passed to
PyArg_ParseTupleAndKewords() to be a const char *kwlist[].
One cast was required as a result of the changes: A type object
mallocs the memory for its tp_doc slot and later frees it.
PyTypeObject says that tp_doc is const char *; but if the type was
created by type_new(), we know it is safe to cast to char *.
This change implements a new bytecode compiler, based on a
transformation of the parse tree to an abstract syntax defined in
Parser/Python.asdl.
The compiler implementation is not complete, but it is in stable
enough shape to run the entire test suite excepting two disabled
tests.
Improve signal handling, especially when using threads, by forcing an early
re-execution of PyEval_EvalFrame() "periodic" code when things_to_do is not
cleared by Py_MakePendingCalls().
M Misc/NEWS
M Python/ceval.c
High level error message was stomping useful detailed messages from lower
level routines.
The new approach is to augment string error messages returned by the low
level routines. The provides both high and low level information. If
the exception value is not a string, no changes are made.
To see the improved messages in action, type:
import random
class R(random): pass
class B(bool): pass
hack: it would resize *interned* strings in-place! This occurred because
their reference counts do not have their expected value -- stringobject.c
hacks them. Mea culpa.
have differing refcount semantics. If anyone sees a prettier way to
acheive the same ends, then please go for it.
I think this is the first time I've ever used Py_XINCREF.
* Fixes an incorrect variable in a PyDict_CheckExact.
* Allow general mapping locals arguments for the execfile() function
and exec statement.
* Add tests.
[ 960406 ] unblock signals in threads
although the changes do not correspond exactly to any patch attached to
that report.
Non-main threads no longer have all signals masked.
A different interface to readline is used.
The handling of signals inside calls to PyOS_Readline is now rather
different.
These changes are all a bit scary! Review and cross-platform testing
much appreciated.
The builtin eval() function now accepts any mapping for the locals argument.
Time sensitive steps guarded by PyDict_CheckExact() to keep from slowing
down the normal case. My timings so no measurable impact.
Add a more informative message for the common user mistake of subclassing
from a module name rather than another class (i.e. random instead of
random.random).
pre-increment forms to post-increment forms. Post-incrementing
also eliminates the need for negative array indices for oparg fetches.
* In exception handling code, check for class based exceptions before
the older string based exceptions.
BINARY_SUBSCR:
* invert test for normal case fall through
* eliminate err handling code by jumping to slow_case
LOAD_LOCALS:
* invert test for normal case fall through
* continue instead of break for the non-error case
STORE_NAME and DELETE_NAME:
* invert test for normal case fall through
LOAD_NAME:
* continue instead of break for the non-error case
DELETE_FAST:
* invert test for normal case fall through
LOAD_DEREF:
* invert test for normal case fall through
* continue instead of break for the non-error case
tests of "why" against WHY_YIELD became useless. This patch removes them,
but assert()s that why != WHY_YIELD everywhere such a test was removed.
The test suite ran fine under a debug build (i.e., the asserts never
triggered).
* Defer error handling for wrong number of arguments to the
unpack_iterable() function. Cuts the code size almost in half.
* Replace function calls to PyList_Size() and PyTuple_Size() with
their smaller and faster macro counterparts.
* Move the constant structure references outside of the inner loops.
(Contributed by Andrew I MacIntyre.)
disables opcode prediction when dynamic execution
profiling is in effect, so the profiling counters at
the top of the main interpreter loop in eval_frame()
are updated for each opcode.
Simplified version of Neal Norwitz's patch which adds gotos for
opcodes that set "why". This skips a number of tests where the
outcome of the tests are known in advance.
A new API (only accessible from C) to interrupt a thread by sending it
an exception. This is not always effective, but might help some people.
Requested by Just van Rossum and Alex Martelli. It is intentional
that you have to write your own C extension to call it from Python.
Docs will have to wait.
* Can now test for basic blocks.
* Optimize inverted comparisions.
* Optimize unary_not followed by a conditional jump.
* Added a new opcode, NOP, to keep code size constant.
* Applied NOP to previous transformations where appropriate.
Note, the NOP would not be necessary if other functions were
added to re-target jump addresses and update the co_lnotab mapping.
That would yield slightly faster and cleaner bytecode at the
expense of optimizer simplicity and of keeping it decoupled
from the line-numbering structure.
Added two predictions:
GET_ITER --> FOR_ITER
FOR_ITER --> STORE_FAST or UNPACK_SEQUENCE
Improves timings on pybench and timeit.py. Pystone results are neutral.
Applied to common cases:
COMPARE_OP is often followed by a JUMP_IF.
JUMP_IF is usually followed by POP_TOP.
Shows improved timings on PyStone, PyBench, and specific tests
using timeit.py:
python timeit.py -s "x=1" "if x==1: pass"
python timeit.py -s "x=1" "if x==2: pass"
python timeit.py -s "x=1" "if x: pass"
python timeit.py -s "x=100" "while x!=1: x-=1"
Potential future candidates:
GET_ITER predicts FOR_ITER
FOR_ITER predicts STORE_FAST or UNPACK_SEQUENCE
Also, applied missing goto fast_next_opcode to DUP_TOPX.
My previous patches should have used fast_next_opcode
in a few places instead of continue.
Also, applied one PyInt_AS_LONG macro in a place where
the type had already been checked.
-DCALL_PROFILE: Count the number of function calls executed.
When this symbol is defined, the ceval mainloop and helper functions
count the number of function calls made. It keeps detailed statistics
about what kind of object was called and whether the call hit any of
the special fast paths in the code.
Optimization:
When we take the fast_function() path, which seems to be taken for
most function calls, and there is minimal frame setup to do, avoid
call PyEval_EvalCodeEx(). The eval code ex function does a lot of
work to handle keywords args and star args, free variables,
generators, etc. The inlined version simply allocates the frame and
copies the arguments values into the frame.
The optimization gets a little help from compile.c which adds a
CO_NOFREE flag to code objects that don't have free variables or cell
variables. This change allows fast_function() to get into the fast
path with fewer tests.
I measure a couple of percent speedup in pystone with this change, but
there's surely more that can be done.
Make the code slightly shorter, faster, and easier to
read.
* Eliminate unused DUP_TOPX code for x==1.
compile.c always generates DUP_TOP instead.
* Since only two cases remain for DUP_TOPX, replace
the switch-case with if-elseif.
* The in-lined integer compare does a CheckExact on
both arguments. Since the second is a little more
likely to fail, test it first.
* The switch-case for IS/IS_NOT and IN/NOT_IN can
separate the regular and inverted cases with no
additional work. For all four paths, saves a test and
jump.
The two are semantically equivalent, but the first triggered a compiler
warning about an unused variable. Note, the preceding steps had already
accessed and decreffed the variable so the reference counts were fine.
parameter being either four or five. Currently, compile.c does not
generate calls with a parameter higher than three.
May have to be reverted if the second alpha or beta shakes out some
other tool generating this op code with a parameter of four or five.
Guido van Rossum
Hye-Shik Chang
Neal Norwitz
Thomas Wouters
Brett Cannon
Georg Brandl
Martin v. Löwis
Jeremy Hylton
Armin Rigo
Barry Warsaw
Phillip J. Eby
Michael W. Hudson
Skip Montanaro
Kurt B. Kaiser
Tim Peters
Raymond Hettinger
Nicholas Bastin
Jack Jansen
Neil Schemenauer
Mark Hammond
Just van Rossum