[Pythonmac-SIG] Proposed Mac OS X change for 2.3.5 and 2.4.1 -
MACOSX_DEPLOYMENT_TARGET vs. Python, round two, fight!
bob at redivi.com
Fri Dec 10 02:17:21 CET 2004
I've included a lot of background information here, if you just want to
know the details
of the proposed change, skip to the bottom.
As some of you may know, Python 2.4's configure script and distutils
tricky behavior with regard to the ``MACOSX_DEPLOYMENT_TARGET``
variable on Mac OS X 10.3 and later. Unless otherwise specified,
assume that I
am talking about a build environment of Mac OS X 10.3 or later. This
is as follows:
If ``MACOSX_DEPLOYMENT_TARGET`` is not set during configure:
1. distutils builds modules with
``-F/Python/Installation/Location -framework Python`` as per usual
behavior if it is also not set
2. If ``MACOSX_DEPLOYMENT_TARGET`` is set during a later run of
distutils complains that "10.3" mismatches the configure time
setting of ""
This Python framework has the following misfeatures:
1. All your extensions are dependent on the installation location of
2. This installation of Python 2.4 *may break the building of
any previous version of Python that uses the same distutils
will certainly break them if they are installed to the same
directory, but if the version of Python 2.3 is early enough, such
stock 2.3.0, it will break that too. Also, any future version of
installed to the same frameworks directory *will break the building
extensions* for this Python installation!
3. The Python framework will not be compatible with versions of Mac OS
earlier than 10.3 anyway due to changes in libSystem!
This is stupid, and it should NOT be default behavior!
If ``MACOSX_DEPLOYMENT_TARGET`` is set to "10.3" or higher during
1. distutils builds modules with ``-undefined dynamic_lookup``
2. If ``MACOSX_DEPLOYMENT_TARGET`` is set to something other than
unset, it will complain that the current setting mismatches the
setting of "10.3"
1. All your extensions are independent of the Python installation
and are thus compatible with any other Python with the same major
2. This installation of Python 2.4 will still, unavoidably, break the
of extensions for any previous version of Python using the bad
behavior mentioned above. This installation is not susceptible to
1. You need to have ``MACOSX_DEPLOYMENT_TARGET`` set during configure,
people don't know to do this.
2. You also need to have ``MACOSX_DEPLOYMENT_TARGET`` set when using
distutils. Even less people know to do this.
The solution to this is to have the following behavior instead:
1. If no ``MACOSX_DEPLOYMENT_TARGET`` is set during configure, and the
machine is Mac OS X 10.3 or later, then set it to "10.3".
2. If no ``MACOSX_DEPLOYMENT_TARGET`` is set during distutils, but it
set during configure, then set it to the configure time value.
3. Otherwise, if it is set to a LOWER value, then fail. Checking for
exact match is bad, because the user or extension author should be
free to build a particular extension using 10.4 specific features
against a Python that is 10.3+ compatible.
For a build machine running Mac OS X 10.2 or earlier, it should ignore
all of this behavior as per usual.
Unless anyone has a reasonable objection to this proposed solution, then
we should make sure it goes into Python 2.4.1 and Python 2.3.5.
These threads might also be of interest:
More information about the Pythonmac-SIG