definitions which do things behind the client pkgs back, in particular
manipulate the library search path
It is well possible that this causes some fallout, but I hope it
will be small and can be dealt with on a per-pkg basis.
(partly) suggested by Mark Davies on tech-pkg
Python 2.7 is intended to be the last major release in the 2.x series.
The Python maintainers are planning to focus their future efforts on
the Python 3.x series.
This means that 2.7 will remain in place for a long time, running
production systems that have not been ported to Python 3.x.
Two consequences of the long-term significance of 2.7 are:
* It's very likely the 2.7 release will have a longer period of
maintenance compared to earlier 2.x versions. Python 2.7 will
continue to be maintained while the transition to 3.x continues, and
the developers are planning to support Python 2.7 with bug-fix
releases beyond the typical two years.
* A policy decision was made to silence warnings only of interest to
developers. :exc:`DeprecationWarning` and its
descendants are now ignored unless otherwise requested, preventing
users from seeing warnings triggered by an application. This change
was also made in the branch that will become Python 3.2. (Discussed
on stdlib-sig and carried out in :issue:`7319`.)
In previous releases, :exc:`DeprecationWarning` messages were
enabled by default, providing Python developers with a clear
indication of where their code may break in a future major version
of Python.
However, there are increasingly many users of Python-based
applications who are not directly involved in the development of
those applications. :exc:`DeprecationWarning` messages are
irrelevant to such users, making them worry about an application
that's actually working correctly and burdening application developers
with responding to these concerns.
You can re-enable display of :exc:`DeprecationWarning` messages by
running Python with the :option:`-Wdefault <-W>` (short form:
:option:`-Wd <-W>`) switch, or by setting the :envvar:`PYTHONWARNINGS`
environment variable to ``"default"`` (or ``"d"``) before running
Python. Python code can also re-enable them
by calling ``warnings.simplefilter('default')``.
