Mailman 3 February 2012 - Python-Dev

PEP 410, 3rd revision, Decimal timestamp
by Victor Stinner 20 Feb '12

20 Feb '12

PEP: 410 Title: Use decimal.Decimal type for timestamps Version: $Revision$ Last-Modified: $Date$ Author: Victor Stinner <victor.stinner(a)haypocalc.com> Status: Draft Type: Standards Track Content-Type: text/x-rst Created: 01-February-2012 Python-Version: 3.3 Abstract ======== Decimal becomes the official type for high-resolution timestamps to make Python support new functions using a nanosecond resolution without loss of precision. Motivation ========== Python 2.3 introduced float timestamps to support sub-second resolutions. os.stat() uses float timestamps by default since Python 2.5. Python 3.3 introduced functions supporting nanosecond resolutions: * os module: futimens(), utimensat() * time module: clock_gettime(), clock_getres(), monotonic(), wallclock() os.stat() reads nanosecond timestamps but returns timestamps as float. The Python float type uses binary64 format of the IEEE 754 standard. With a resolution of one nanosecond (10\ :sup:`-9`), float timestamps lose precision for values bigger than 2\ :sup:`24` seconds (194 days: 1970-07-14 for an Epoch timestamp). Nanosecond resolution is required to set the exact modification time on filesystems supporting nanosecond timestamps (e.g. ext4, btrfs, NTFS, ...). It helps also to compare the modification time to check if a file is newer than another file. Use cases: copy the modification time of a file using shutil.copystat(), create a TAR archive with the tarfile module, manage a mailbox with the mailbox module, etc. An arbitrary resolution is preferred over a fixed resolution (like nanosecond) to not have to change the API when a better resolution is required. For example, the NTP protocol uses fractions of 2\ :sup:`32` seconds (approximatively 2.3 × 10\ :sup:`-10` second), whereas the NTP protocol version 4 uses fractions of 2\ :sup:`64` seconds (5.4 × 10\ :sup:`-20` second). .. note:: With a resolution of 1 microsecond (10\ :sup:`-6`), float timestamps lose precision for values bigger than 2\ :sup:`33` seconds (272 years: 2242-03-16 for an Epoch timestamp). With a resolution of 100 nanoseconds (10\ :sup:`-7`, resolution used on Windows), float timestamps lose precision for values bigger than 2\ :sup:`29` seconds (17 years: 1987-01-05 for an Epoch timestamp). Specification ============= Add decimal.Decimal as a new type for timestamps. Decimal supports any timestamp resolution, support arithmetic operations and is comparable. It is possible to coerce a Decimal to float, even if the conversion may lose precision. The clock resolution can also be stored in a Decimal object. Add an optional *timestamp* argument to: * os module: fstat(), fstatat(), lstat(), stat() (st_atime, st_ctime and st_mtime fields of the stat structure), sched_rr_get_interval(), times(), wait3() and wait4() * resource module: ru_utime and ru_stime fields of getrusage() * signal module: getitimer(), setitimer() * time module: clock(), clock_gettime(), clock_getres(), monotonic(), time() and wallclock() The *timestamp* argument value can be float or Decimal, float is still the default for backward compatibility. The following functions support Decimal as input: * datetime module: date.fromtimestamp(), datetime.fromtimestamp() and datetime.utcfromtimestamp() * os module: futimes(), futimesat(), lutimes(), utime() * select module: epoll.poll(), kqueue.control(), select() * signal module: setitimer(), sigtimedwait() * time module: ctime(), gmtime(), localtime(), sleep() The os.stat_float_times() function is deprecated: use an explicit cast using int() instead. .. note:: The decimal module is implemented in Python and is slower than float, but there is a new C implementation which is almost ready for inclusion in CPython. Backwards Compatibility ======================= The default timestamp type is unchanged, so there is no impact on backward compatibility nor on performances. The new timestamp type, decimal.Decimal, is only returned when requested explicitly. Objection: clocks accuracy ========================== Computer clocks and operating systems are inaccurate and fail to provide nanosecond accuracy in practice. A nanosecond is what it takes to execute a couple of CPU instructions. Even on a real-time operating system, a nanosecond-precise measurement is already obsolete when it starts being processed by the higher-level application. A single cache miss in the CPU will make the precision worthless. .. note:: Linux *actually* is able to measure time in nanosecond precision, even though it is not able to keep its clock synchronized to UTC with a nanosecond accuracy. Alternatives: Timestamp types ============================= To support timestamps with an arbitrary or nanosecond resolution, the following types have been considered: * number of nanoseconds * 128-bits float * decimal.Decimal * datetime.datetime * datetime.timedelta * tuple of integers * timespec structure Criteria: * Doing arithmetic on timestamps must be possible * Timestamps must be comparable * An arbitrary resolution, or at least a resolution of one nanosecond without losing precision * It should be possible to coerce the new timestamp to float for backward compatibility A resolution of one nanosecond is enough to support all current C functions. The best resolution used by operating systems is one nanosecond. In practice, most clock accuracy is closer to microseconds than nanoseconds. So it sounds reasonable to use a fixed resolution of one nanosecond. Number of nanoseconds (int) --------------------------- A nanosecond resolution is enough for all current C functions and so a timestamp can simply be a number of nanoseconds, an integer, not a float. The number of nanoseconds format has been rejected because it would require to add new specialized functions for this format because it not possible to differentiate a number of nanoseconds and a number of seconds just by checking the object type. 128-bits float -------------- Add a new IEEE 754-2008 quad-precision binary float type. The IEEE 754-2008 quad precision float has 1 sign bit, 15 bits of exponent and 112 bits of mantissa. 128-bits float is supported by GCC (4.3), Clang and ICC compilers. Python must be portable and so cannot rely on a type only available on some platforms. For example, Visual C++ 2008 doesn't support 128-bits float, whereas it is used to build the official Windows executables. Another example: GCC 4.3 does not support __float128 in 32-bit mode on x86 (but GCC 4.4 does). There is also a license issue: GCC uses the MPFR library for 128-bits float, library distributed under the GNU LGPL license. This license is not compatible with the Python license. .. note:: The x87 floating point unit of Intel CPU supports 80-bit floats. This format is not supported by the SSE instruction set, which is now preferred over float, especially on x86_64. Other CPU vendors don't support 80-bit float. datetime.datetime ----------------- The datetime.datetime type is the natural choice for a timestamp because it is clear that this type contains a timestamp, whereas int, float and Decimal are raw numbers. It is an absolute timestamp and so is well defined. It gives direct access to the year, month, day, hours, minutes and seconds. It has methods related to time like methods to format the timestamp as string (e.g. datetime.datetime.strftime). The major issue is that except os.stat(), time.time() and time.clock_gettime(time.CLOCK_GETTIME), all time functions have an unspecified starting point and no timezone information, and so cannot be converted to datetime.datetime. datetime.datetime has also issues with timezone. For example, a datetime object without timezone (unaware) and a datetime with a timezone (aware) cannot be compared. There is also an ordering issues with daylight saving time (DST) in the duplicate hour of switching from DST to normal time. datetime.datetime has been rejected because it cannot be used for functions using an unspecified starting point like os.times() or time.clock(). For time.time() and time.clock_gettime(time.CLOCK_GETTIME): it is already possible to get the current time as a datetime.datetime object using:: datetime.datetime.now(datetime.timezone.utc) For os.stat(), it is simple to create a datetime.datetime object from a decimal.Decimal timestamp in the UTC timezone:: datetime.datetime.fromtimestamp(value, datetime.timezone.utc) .. note:: datetime.datetime only supports microsecond resolution, but can be enhanced to support nanosecond. datetime.timedelta ------------------ datetime.timedelta is the natural choice for a relative timestamp because it is clear that this type contains a timestamp, whereas int, float and Decimal are raw numbers. It can be used with datetime.datetime to get an absolute timestamp when the starting point is known. datetime.timedelta has been rejected because it cannot be coerced to float and has a fixed resolution. One new standard timestamp type is enough, Decimal is preferred over datetime.timedelta. Converting a datetime.timedelta to float requires an explicit call to the datetime.timedelta.total_seconds() method. .. note:: datetime.timedelta only supports microsecond resolution, but can be enhanced to support nanosecond. .. _tuple: Tuple of integers ----------------- To expose C functions in Python, a tuple of integers is the natural choice to store a timestamp because the C language uses structures with integers fields (e.g. timeval and timespec structures). Using only integers avoids the loss of precision (Python supports integers of arbitrary length). Creating and parsing a tuple of integers is simple and fast. Depending of the exact format of the tuple, the precision can be arbitrary or fixed. The precision can be choose as the loss of precision is smaller than an arbitrary limit like one nanosecond. Different formats has been proposed: * A: (numerator, denominator) * value = numerator / denominator * resolution = 1 / denominator * denominator > 0 * B: (seconds, numerator, denominator) * value = seconds + numerator / denominator * resolution = 1 / denominator * 0 <= numerator < denominator * denominator > 0 * C: (intpart, floatpart, base, exponent) * value = intpart + floatpart / base\ :sup:`exponent` * resolution = 1 / base \ :sup:`exponent` * 0 <= floatpart < base \ :sup:`exponent` * base > 0 * exponent >= 0 * D: (intpart, floatpart, exponent) * value = intpart + floatpart / 10\ :sup:`exponent` * resolution = 1 / 10 \ :sup:`exponent` * 0 <= floatpart < 10 \ :sup:`exponent` * exponent >= 0 * E: (sec, nsec) * value = sec + nsec × 10\ :sup:`-9` * resolution = 10 \ :sup:`-9` (nanosecond) * 0 <= nsec < 10 \ :sup:`9` All formats support an arbitrary resolution, except of the format (E). The format (D) may not be able to store the exact value (may loss of precision) if the clock frequency is arbitrary and cannot be expressed as a power of 10. The format (C) has a similar issue, but in such case, it is possible to use base=frequency and exponent=1. The formats (C), (D) and (E) allow optimization for conversion to float if the base is 2 and to decimal.Decimal if the base is 10. The format (A) is a simple fraction. It supports arbitrary precision, is simple (only two fields), only requires a simple division to get the floating point value, and is already used by float.as_integer_ratio(). To simplify the implementation (especially the C implementation to avoid integer overflow), a numerator bigger than the denominator can be accepted. The tuple may be normalized later. Tuple of integers have been rejected because they don't support arithmetic operations. .. note:: On Windows, the ``QueryPerformanceCounter()`` clock uses the frequency of the processor which is an arbitrary number and so may not be a power or 2 or 10. The frequency can be read using ``QueryPerformanceFrequency()``. timespec structure ------------------ timespec is the C structure used to store timestamp with a nanosecond resolution. Python can use a type with the same structure: (seconds, nanoseconds). For convenience, arithmetic operations on timespec are supported. Example of an incomplete timespec type supporting addition, subtraction and coercion to float:: class timespec(tuple): def __new__(cls, sec, nsec): if not isinstance(sec, int): raise TypeError if not isinstance(nsec, int): raise TypeError asec, nsec = divmod(nsec, 10 ** 9) sec += asec obj = tuple.__new__(cls, (sec, nsec)) obj.sec = sec obj.nsec = nsec return obj def __float__(self): return self.sec + self.nsec * 1e-9 def total_nanoseconds(self): return self.sec * 10 ** 9 + self.nsec def __add__(self, other): if not isinstance(other, timespec): raise TypeError ns_sum = self.total_nanoseconds() + other.total_nanoseconds() return timespec(*divmod(ns_sum, 10 ** 9)) def __sub__(self, other): if not isinstance(other, timespec): raise TypeError ns_diff = self.total_nanoseconds() - other.total_nanoseconds() return timespec(*divmod(ns_diff, 10 ** 9)) def __str__(self): if self.sec < 0 and self.nsec: sec = abs(1 + self.sec) nsec = 10**9 - self.nsec return '-%i.%09u' % (sec, nsec) else: return '%i.%09u' % (self.sec, self.nsec) def __repr__(self): return '<timespec(%s, %s)>' % (self.sec, self.nsec) The timespec type is similar to the format (E) of tuples of integer, except that it supports arithmetic and coercion to float. The timespec type was rejected because it only supports nanosecond resolution and requires to implement each arithmetic operation, whereas the Decimal type is already implemented and well tested. Alternatives: API design ======================== Add a string argument to specify the return type ------------------------------------------------ Add an string argument to function returning timestamps, example: time.time(format="datetime"). A string is more extensible than a type: it is possible to request a format that has no type, like a tuple of integers. This API was rejected because it was necessary to import implicitly modules to instantiate objects (e.g. import datetime to create datetime.datetime). Importing a module may raise an exception and may be slow, such behaviour is unexpected and surprising. Add a global flag to change the timestamp type ---------------------------------------------- A global flag like os.stat_decimal_times(), similar to os.stat_float_times(), can be added to set globally the timestamp type. A global flag may cause issues with libraries and applications expecting float instead of Decimal. Decimal is not fully compatible with float. float+Decimal raises a TypeError for example. The os.stat_float_times() case is different because an int can be coerced to float and int+float gives float. Add a protocol to create a timestamp ------------------------------------ Instead of hard coding how timestamps are created, a new protocol can be added to create a timestamp from a fraction. For example, time.time(timestamp=type) would call the class method type.__fromfraction__(numerator, denominator) to create a timestamp object of the specified type. If the type doesn't support the protocol, a fallback is used: type(numerator) / type(denominator). A variant is to use a "converter" callback to create a timestamp. Example creating a float timestamp: def timestamp_to_float(numerator, denominator): return float(numerator) / float(denominator) Common converters can be provided by time, datetime and other modules, or maybe a specific "hires" module. Users can define their own converters. Such protocol has a limitation: the timestamp structure has to be decided once and cannot be changed later. For example, adding a timezone or the absolute start of the timestamp would break the API. The protocol proposition was as being excessive given the requirements, but that the specific syntax proposed (time.time(timestamp=type)) allows this to be introduced later if compelling use cases are discovered. .. note:: Other formats may be used instead of a fraction: see the tuple of integers section for example. Add new fields to os.stat ------------------------- To get the creation, modification and access time of a file with a nanosecond resolution, three fields can be added to os.stat() structure. The new fields can be timestamps with nanosecond resolution (e.g. Decimal) or the nanosecond part of each timestamp (int). If the new fields are timestamps with nanosecond resolution, populating the extra fields would be time consuming. Any call to os.stat() would be slower, even if os.stat() is only called to check if a file exists. A parameter can be added to os.stat() to make these fields optional, the structure would have a variable number of fields. If the new fields only contain the fractional part (nanoseconds), os.stat() would be efficient. These fields would always be present and so set to zero if the operating system does not support sub-second resolution. Splitting a timestamp in two parts, seconds and nanoseconds, is similar to the timespec type and tuple of integers, and so have the same drawbacks. Adding new fields to the os.stat() structure does not solve the nanosecond issue in other modules (e.g. the time module). Add a boolean argument ---------------------- Because we only need one new type (Decimal), a simple boolean flag can be added. Example: time.time(decimal=True) or time.time(hires=True). Such flag would require to do an hidden import which is considered as a bad practice. The boolean argument API was rejected because it is not "pythonic". Changing the return type with a parameter value is preferred over a boolean parameter (a flag). Add new functions ----------------- Add new functions for each type, examples: * time.clock_decimal() * time.time_decimal() * os.stat_decimal() * os.stat_timespec() * etc. Adding a new function for each function creating timestamps duplicate a lot of code and would be a pain to maintain. Add a new hires module ---------------------- Add a new module called "hires" with the same API than the time module, except that it would return timestamp with high resolution, e.g. decimal.Decimal. Adding a new module avoids to link low-level modules like time or os to the decimal module. This idea was rejected because it requires to duplicate most of the code of the time module, would be a pain to maintain, and timestamps are used modules other than the time module. Examples: signal.sigtimedwait(), select.select(), resource.getrusage(), os.stat(), etc. Duplicate the code of each module is not acceptable. Links ===== Python: * `Issue #7652: Merge C version of decimal into py3k <http://bugs.python.org/issue7652>`_ (cdecimal) * `Issue #11457: os.stat(): add new fields to get timestamps as Decimal objects with nanosecond resolution <http://bugs.python.org/issue11457>`_ * `Issue #13882: PEP 410: Use decimal.Decimal type for timestamps <http://bugs.python.org/issue13882>`_ * `[Python-Dev] Store timestamps as decimal.Decimal objects <http://mail.python.org/pipermail/python-dev/2012-January/116025.html>`_ Other languages: * Ruby (1.9.3), the `Time class <http://ruby-doc.org/core-1.9.3/Time.html>`_ supports picosecond (10\ :sup:`-12`) * .NET framework, `DateTime type <http://msdn.microsoft.com/en-us/library/system.datetime.ticks.aspx>`_: number of 100-nanosecond intervals that have elapsed since 12:00:00 midnight, January 1, 0001. DateTime.Ticks uses a signed 64-bit integer. * Java (1.5), `System.nanoTime() <http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/System.html#nanoTime…>`_: wallclock with an unspecified starting point as a number of nanoseconds, use a signed 64 bits integer (long). * Perl, `Time::Hiref module <http://perldoc.perl.org/Time/HiRes.html>`_: use float so has the same loss of precision issue with nanosecond resolution than Python float timestamps Copyright ========= This document has been placed in the public domain.

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Re: [Python-Dev] cpython: add generic implementation of a __dict__ descriptor for C types
by Georg Brandl 20 Feb '12

20 Feb '12

Am 20.02.2012 02:04, schrieb benjamin.peterson: > http://hg.python.org/cpython/rev/78f93eb7dd75 > changeset: 75050:78f93eb7dd75 > user: Benjamin Peterson <benjamin(a)python.org> > date: Sun Feb 19 19:59:10 2012 -0500 > summary: > add generic implementation of a __dict__ descriptor for C types > > files: > Doc/c-api/object.rst | 12 +++++++++ > Doc/c-api/type.rst | 1 - > Include/object.h | 2 + > Misc/NEWS | 4 +++ > Objects/object.c | 42 ++++++++++++++++++++++++++++++++ > Objects/typeobject.c | 22 +++------------- > 6 files changed, 64 insertions(+), 19 deletions(-) > > > diff --git a/Doc/c-api/object.rst b/Doc/c-api/object.rst > --- a/Doc/c-api/object.rst > +++ b/Doc/c-api/object.rst > @@ -101,6 +101,18 @@ > This is the equivalent of the Python statement ``del o.attr_name``. > > > +.. c:function:: PyObject* PyType_GenericGetDict(PyObject *o, void *context) > + > + A generic implementation for the getter of a ``__dict__`` descriptor. It > + creates the dictionary if necessary. > + > + > +.. c:function:: int PyType_GenericSetDict(PyObject *o, void *context) > + > + A generic implementation for the setter of a ``__dict__`` descriptor. This > + implementation does not allow the dictionary to be deleted. > + > + > .. c:function:: PyObject* PyObject_RichCompare(PyObject *o1, PyObject *o2, int opid) versionadded, please? Georg

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Re: [Python-Dev] [Python-checkins] cpython: Fix a failing importlib test under Windows.
by Nick Coghlan 20 Feb '12

20 Feb '12

On Mon, Feb 20, 2012 at 10:36 AM, brett.cannon <python-checkins(a)python.org> wrote: > - if sys_module.platform in CASE_INSENSITIVE_PLATFORMS: > + if any(sys_module.platform.startswith(x) > + for x in CASE_INSENSITIVE_PLATFORMS): Since C_I_P is a tuple, that condition can be written as: "sys_module.platform.startswith(CASE_INSENSITIVE_PLATFORMS)" Cheers, Nick. -- Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia

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Links to last binary builds to download pages
by Michael Foord 20 Feb '12

20 Feb '12

Hey folks, When we do security only releases of Python we regularly get emails to webmaster(a)python.org asking where to find binary builds. If you want to find the most recent binary builds of Python 2.5 & 2.6, it used to involve clicking through quite a few links. I've added links to the latest binary releases to the 2.6.7, 2.5.6 and 2.5.5 security release download pages. These are primarily for the benefit of Windows and Mac OS X users who wouldn't normally compile their own builds from source. It would be helpful if release managers for security, source only, releases could include similar links in future. All the best, Michael -- http://www.voidspace.org.uk/ May you do good and not evil May you find forgiveness for yourself and forgive others May you share freely, never taking more than you give. -- the sqlite blessing http://www.sqlite.org/different.html

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PEP for new dictionary implementation
by Mark Shannon 20 Feb '12

20 Feb '12

Proposed PEP for new dictionary implementation, PEP 410? is attached. Cheers, Mark. PEP: XXX Title: Key-Sharing Dictionary Version: $Revision$ Last-Modified: $Date$ Author: Mark Shannon <mark(a)hotpy.org> Status: Draft Type: Standards Track Content-Type: text/x-rst Created: 08-Feb-2012 Python-Version: 3.3 or 3.4 Post-History: 08-Feb-2012 Abstract ======== This PEP proposes a change in the implementation of the builtin dictionary type ``dict``. The new implementation allows dictionaries which are used as attribute dictionaries (the ``__dict__`` attribute of an object) to share keys with other attribute dictionaries of instances of the same class. Motivation ========== The current dictionary implementation uses more memory than is necessary when used as a container for object attributes as the keys are replicated for each instance rather than being shared across many instances of the same class. Despite this, the current dictionary implementation is finely tuned and performs very well as a general-purpose mapping object. By separating the keys (and hashes) from the values it is possible to share the keys between multiple dictionaries and improve memory use. By ensuring that keys are separated from the values only when beneficial, it is possible to retain the high-performance of the current dictionary implementation when used as a general-purpose mapping object. Behaviour ========= The new dictionary behaves in the same way as the old implementation. It fully conforms to the Python API, the C API and the ABI. Performance =========== Memory Usage ------------ Reduction in memory use is directly related to the number of dictionaries with shared keys in existence at any time. These dictionaries are typically half the size of the current dictionary implementation. Benchmarking shows that memory use is reduced by 10% to 20% for object-oriented programs with no significant change in memory use for other programs. Speed ----- The performance of the new implementation is dominated by memory locality effects. When keys are not shared (for example in module dictionaries and dictionary explicitly created by dict() or {} ) then performance is unchanged (within a percent or two) from the current implementation. For the shared keys case, the new implementation tends to separate keys from values, but reduces total memory usage. This will improve performance in many cases as the effects of reduced memory usage outweigh the loss of locality, but some programs may show a small slow down. Benchmarking shows no significant change of speed for most benchmarks. Object-oriented benchmarks show small speed ups when they create large numbers of objects of the same class (the gcbench benchmark shows a 10% speed up; this is likely to be an upper limit). Implementation ============== Both the old and new dictionaries consist of a fixed-sized dict struct and a re-sizeable table. In the new dictionary the table can be further split into a keys table and values array. The keys table holds the keys and hashes and (for non-split tables) the values as well. It differs only from the original implementation in that it contains a number of fields that were previously in the dict struct. If a table is split the values in the keys table are ignored, instead the values are held in a separate array. Split-Table dictionaries ------------------------ When dictionaries are created to fill the __dict__ slot of an object, they are created in split form. The keys table is cached in the type, potentially allowing all attribute dictionaries of instances of one class to share keys. In the event of the keys of these dictionaries starting to diverge, individual dictionaries will lazily convert to the combined-table form. This ensures good memory use in the common case, and correctness in all cases. Combined-Table dictionaries --------------------------- Explicit dictionaries (dict() or {}), module dictionaries and most other dictionaries are created as combined-table dictionaries. A combined-table dictionary never becomes a split-table dictionary. Combined tables are laid out in much the same way as the tables in the old dictionary, resulting in very similar performance. Implementation ============== The new dictionary implementation is available at [1]_. Pros and Cons ============= Pros ---- Significant memory savings for object-oriented applications. Small improvement to speed for programs which create lots of objects. Cons ---- Change to data structures: Third party modules which meddle with the internals of the dictionary implementation will break. Changes to repr() output and iteration order: For most cases, this will be unchanged. However for some split-table dictionaries the iteration order will change. Neither of these cons should be a problem. Modules which meddle with the internals of the dictionary implementation are already broken and should be fixed to use the API. The iteration order of dictionaries was never defined and has always been arbitrary; it is different for Jython and PyPy. References ========== .. [1] Reference Implementation: https://bitbucket.org/markshannon/cpython_new_dict Copyright ========= This document has been placed in the public domain.

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PEP 394 accepted
by "Martin v. Löwis" 19 Feb '12

19 Feb '12

As the PEP czar for PEP 394, I have reviewed it and am happy to say that I can accept it. I suppose that Nick will keep track of actually implementing it in Python 2.7. Regards, Martin

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Re: [Python-Dev] cpython: allow arbitrary attributes on classmethod and staticmethod (closes #14051)
by Antoine Pitrou 19 Feb '12

19 Feb '12

Hi, > +static PyObject * > +cm_get___dict__(classmethod *cm, void *closure) > +{ > + Py_INCREF(cm->cm_dict); > + return cm->cm_dict; > +} >>> def f(): pass ... >>> cm = classmethod(f) >>> cm.__dict__ Erreur de segmentation Regards Antoine.

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compiling cpython in visual studio 2010
by Ejaj Hassan 19 Feb '12

19 Feb '12

Hello everyone, I am trying to work on Python bugs following the tutorial given in the python website. I have installed Tortoise svn and visual studio 2010, I cloned a copy of cpython as it is advised in the website using, however I am having some problem in compiling it using visual studio 2010. I request someone to kindly make me understand the full steps on solving the bugs. With regards, Ejaj Hassan

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PEP 394 request for pronouncement (python2 symlink in *nix systems)
by Nick Coghlan 19 Feb '12

19 Feb '12

PEP 394 [1] aims to document our collective recommendation for allowing shebang lines to specifically request some version of 2.x, without requiring that it be exactly 2.7 (or 2.6, etc). I'd let this drift for a while, but the imminent release of 2.7.3 makes it necessary to push for a final pronouncement. Kerrick has the necessary Makefile.pre.in patch up on the tracker [2] to add the hard link for the python2 name. We could, of course, make the recommendation to distributions without updating "make install" and "make bininstall" to follow our own advice, but that seems needlessly inconsistent. [1] http://www.python.org/dev/peps/pep-0394/ [2] http://bugs.python.org/issue12627 Regards, Nick. -- Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia

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Re: [Python-Dev] Status of PEP 397 - Python launcher for Windows
by Paul Moore 19 Feb '12

19 Feb '12

On 19 February 2012 03:09, Mark Hammond <mhammond(a)skippinet.com.au> wrote: > Thanks for the note Paul, but did you also mean to CC python-dev? Yes, I did, sorry. > > On 18/02/2012 9:15 PM, Paul Moore wrote: >> >> On 18 February 2012 05:24, Mark Hammond<skippy.hammond(a)gmail.com> wrote: >>> >>> I'm wondering what thoughts are on PEP 397, the Python launcher for >>> Windows. >>> I've been using the implementation for a number of months now and I find >>> it >>> incredibly useful. >> >> >> I use it all the time. It's extremely useful, and I wouldn't be without >> it. >> >> [OT: One interesting property I find useful - if you put an alias >> "vpython=python.exe" in the ini file (no path to Python) then >> #!vpython picks up whatever Python is on PATH - this can be very >> useful if you use virtualenvs a lot and want to run a script with the >> current virtualenv] >> >>> Thoughts or comments? >> >> >> IIRC, one question was how to manage multiple installs - if I install >> Python 3.3 and 3.4, both of which install py.exe, and then uninstall >> one, what happens to py.exe. What if I then uninstall the second? >> Reference count the launcher? >> >> If it were possible to package up the launcher installer with the >> Python installer, but then install it as a separate item, that might >> be best (it's what MS products seem to do a lot - install one, get ten >> extra - I don't like the way MS do it, but it seems appropriate here). >> This would also allow python.org to host a standalone version of the >> installer which could be installed seamlessly for older versions. >> >> Paul > >

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