A question I occasionally get asked by organisations that use Python
commercially but don't currently employ any core developers themselves
is "How can we prioritise getting particular issues
A related problem we have in the PSF is knowing which core developers
are available for freelance & consulting work when organisations
approach us regarding larger projects. At the moment, those kinds of
referrals are reliant on Board members' personal knowledge of who
amongst the core development team is open to that style of employment
and making direct introductions, which is neither transparent nor
As such, what do folks think of the idea of a new, *opt-in* section in
the developer guide, similar to the current experts index, but
allowing core developers to indicate the ways in which we're willing
to provide paid support.
I'd see four likely sections in such a document:
* Freelance consultants: folks that are available for contract
opportunities at the individual level
* Consulting companies: folks that are available for contract
opportunities, but work for larger consulting organisations rather
than contracting directly
* Commercial redistributors: folks that work for commercial Python
redistributors and are willing and able to both help in getting
customer issues resolved and in acting as a point of escalation for
* Direct employment: folks that work directly for organisations that
use Python extensively, and hence are able to act as a point of
escalation for their colleagues
The latter three categories would be further broken out by employer,
while the first would just be a list of names and professional contact
P.S. Disclosure: I do have my own interests in mind here, both
personally and professionally. At a personal level, I'm a strong
believer in "If you want me to care about your opinion on how I spend
my time, pay me", so it makes sense to me to make it easy for more
commercially-minded core developers to say "Pay me or my employer if
you'd like to influence my time allocation". Professionally, it's
definitely in my interests for both Python core developers and
commercial Python redistributors to be recognised as a group for their
expertise and overall influence on the technology sector.
Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia
(I forget exactly who to contact about the certificate, so I'm going
slightly more broad.)
The PSF's certificate we use to sign binaries and the installer for
Windows is a SHA-1 certificate, which has been deprecated as of the
start of the year: http://aka.ms/sha1
Already Windows may warn about the certificate on our current and past
releases, but because the signature is timestamped prior to 01Jan2016 it
will not be blocked. However, our next releases will be blocked (with a
bypass available) unless we update the certificate to SHA-2.
Some sources have suggested that CAs will provide a SHA-2 certificate
for free on request.
Supporting Windows Vista and Windows Server 2008 appears to be
complicated, according to the link I gave above. I want to test the
effect of only signing with SHA-2 on those platforms and make a
recommendation based on that, rather than trying to guess what will
happen (those OSs did not block downloaded files as aggressively as
Happy to take this off list once I know who handles this certificate.
at this year's EuroPython we'll have a new officially supported
feature, the panel discussion, and we (I'm one of the organizers)
thought it would be big fun to have a panel of core developers
talk about the merits of computed gotos, micro benchmarks,
adding fast-paths for integer, free lists, and all those nifty
things that core devs do in their spare time ;-)
No, seriously, this is great stuff normal Python users never get
to see and that's really a shame.
So my question to you: will some of you attend EuroPython this
year and would you be willing to talk on a panel ?
* EuroPython 2016
* Location: Bilbao, Basque Country, Spain
* Dates: July 17-24
* CFP just opened: https://ep2016.europython.eu/en/call-for-proposals/
(and will close again in just two weeks)
* Everything else, just a click away: https://ep2016.europython.eu/
* For reference, last year: https://ep2015.europython.eu/
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in the past I suggested to document our deprecation policy on a PEP.
Since the issue came up again on a few issues on the tracker and on
#python-dev, I adapted the content of my previous email and wrote a
Attached you can find the full text, including references to the
previous discussions on python-dev and related issues.
Title: Deprecation Policy
Author: Ezio Melotti <ezio.melotti(a)gmail.com>
The goal of this PEP is to document when and how to deprecate
APIs in the Python language and in the standard library.
Python doesn't currently have a documented policy regarding
deprecations. This leads to repeated discussions and
inconsistencies in how we handle and document deprecations
[#]_ [#]_ [#]_ [#]_ [#]_ [#]_ [#]_.
What and when to deprecate
* An API can be deprecated if a better alternative exists, if the
implementation is incorrect or obsolete, or if the name or module
has been changed. If possible, an alternative should be provided.
* If the API is public, it must go through the deprecation
process. If the API is private or provisional, it might.
* The number of releases before an API is removed is decided
on a case-by-case basis depending on widely used the API is,
in which Python versions the alternative is available, which
Python versions are currently supported by different operating
systems, distros, and projects, and how easy it is to replace
* In general it's better to be conservative, and if the API is
deprecated in ``3.X``, it shouldn't be removed before ``3.X+2``.
This should also take into account which Python versions are
Porting from 2.x to 3.x
Some APIs that are available in Python 2.7 might get deprecated
in Python 3, and people that upgrade directly from 2.7 to 3.X might
not see any warnings.
In order to make porting code to 3.X easier:
* nothing that is available and not deprecated in 2.7 should be
removed from Python 3 as long as 2.7 is officially supported;
* deprecation warnings can be backported to 2.7 and enabled
using the ``-3`` flag;
Python offers two kinds of deprecation warnings:
Initially, only ``PendingDeprecationWarning``\ s were silenced by
default. Starting from Python 2.7, ``DeprecationWarning``\ s
are also silenced by default [#]_ [#]_.
Since this distinction is no longer true:
* ``PendingDeprecationWarning`` should not be used
* ``DeprecationWarning`` will be used for all deprecations
``PendingDeprecationWarning`` won't be removed, and 3rd-party
projects are allowed to use it as they see fit.
In the past, the following deprecation progression has been used:
1. in release ``3.X`` a ``PendingDeprecationWarning`` is added
2. in release ``3.X+1`` it becomes a ``DeprecationWarning``
3. in release ``3.X+2`` the API is removed
The warning were occasionally left for more than one release,
either intentionally or because no one remembered to update them.
Since ``PendingDeprecationWarning`` should no longer be used, this
can be simplified to:
1. in release ``3.X`` a ``DeprecationWarning`` is added
2. in release ``3.X+N`` the API is removed
``N`` can be ``>=1``, should be decided beforehand, and should be
These are the steps required to deprecate and remove an API:
1. propose to deprecate an API on a tracker issue or on python-dev
and decide in which version it will be removed.
2. attach to the issue a patch to deprecate the API that:
* adds a ``DeprecationWarning`` to the code
* adds the deprecation to the documentation
* adds a test to verify that the warning is raised
* possibly updates code/examples that uses the deprecated API
3. after review, apply the patch to the current in-development
branch and close the issue.
4. attach to a separate issue a patch to remove the API that:
* removes the API and the warning
* removes the tests for the API and for the deprecation
* removes the API documentation
5. once the designated branch is available, apply the patch and
close the issue.
When a deprecated API is used, a ``DeprecationWarning`` should
be raised. The message should mention that the API is
deprecated, and if possible it should indicate when it will be
removed and what should be used instead.
These messages are intended for developers, and are therefore
hidden by default to prevent end-users to see them.
These messages should be enabled by default in places where only
developers will see them, such as tests [#]_ and in the interactive
Documenting the deprecations
* All deprecations should be documented in the docs, using the
* If an alternative is available, it should be mentioned, possibly
* Each "what's new" document should include either a section or a
link to a separate document [#]_ listing all the new deprecations,
the APIs that have been removed and possibly the planned
removals for the upcoming releases. This could be generated
automatically with Sphinx.
* Simply removing the documentation for deprecated APIs is
not acceptable, since people that see the API used in the
code won't know if they can still use the API or not.
Deprecation warnings rendering
On one hand deprecation warnings should be clearly visible, on the
other hand we want to avoid riddling the docs with red boxes [#]_.
In order to find a balance between the two:
* Individual functions/methods/attributes should have a label next
to the name to indicate the deprecation, and a more verbose
description underneath. The label will be red, the description
doesn't have to [#]_.
* Modules and classes can use a red warning box. If the
documentation spans more than a single screen of text, additional
warning labels can be added to the individual functions/methods.
* Links to deprecated objects should be marked differently.
This will require some tweak to the ``deprecated-removed``
directive, in order to produce different CSS classes for
modules/classes, functions/methods/attributes, and links.
Updating deprecated code
As mentioned above, the error messages and documentation should
provide an alternative whenever possible. When the alternative
is not straightforward, more complex examples or a new section
can added to the documentation to explain how to convert the code.
Another option is to write scripts that can automatically update
Python code to use the new alternative. This requires:
1. writing a 3to3 tool similar to (and possibly based on) 2to3;
2. documenting clearly its API and providing several examples;
3. providing fixers for deprecated APIs that can be used to
automatically update deprecated code;
This can be done as a GSoC project, and if done correctly, it will
provide an easy way for people to upgrade their codebases.
* :pep:`387` -- Backwards Compatibility Policy
* :pep:`4` -- Deprecation of Standard Modules
.. [#] Deprecation Policy
.. [#] Deprecation Policy
.. [#] deprecated in 3.2/3.3, should be removed in 3.5 or ???
.. [#] DeprecationWarning for PEP 479 (generator_stop)
.. [#] Deprecate threading.Thread.isDaemon etc
.. [#] Remove the Deprecated API in trace module
.. [#] Resurrect inspect.getargspec() in 3.6
.. [#] What's New in Python 2.7 -- Changes to the Handling of
Deprecation Warnings (https://docs.python.org/3/whatsnew/2.7.html)
.. [#] Silence DeprecationWarning by default
.. [#] Enable warnings by default in unittest
.. [#] DeprecationWarnings should be visible by default in the
interactive REPL (https://bugs.python.org/issue24294)
.. [#] Django has a "Django Deprecation Timeline" page
.. [#] Consistent documentation practices for security concerns
and considerations (https://bugs.python.org/issue13515)
.. [#] Put "deprecated" warnings first
This document has been placed in the public domain.