Building a Python Mac OS X distribution
=======================================

The ``build-install.py`` script creates Python distributions, including
certain third-party libraries as necessary.  It builds a complete
framework-based Python out-of-tree, installs it in a funny place with
$DESTROOT, massages that installation to remove .pyc files and such, creates
an Installer package from the installation plus other files in ``resources``
and ``scripts`` and placed that on a ``.dmg`` disk image.

For Python 3.4.0, PSF practice is to build two installer variants
for each release.

1.  32-bit-only, i386 and PPC universal, capable on running on all machines
    supported by Mac OS X 10.5 through (at least) 10.9::

        /path/to/bootstrap/python2.7 build-installer.py \
            --sdk-path=/Developer/SDKs/MacOSX10.5.sdk \
            --universal-archs=32-bit \
            --dep-target=10.5

    - builds the following third-party libraries

        * NCurses 5.9 (http://bugs.python.org/issue15037)
        * SQLite 3.8.11
        * XZ 5.0.5

    - uses system-supplied versions of third-party libraries

        * readline module links with Apple BSD editline (libedit)

    - requires ActiveState ``Tcl/Tk 8.4`` (currently 8.4.20) to be installed for building

    - recommended build environment:

        * Mac OS X 10.5.8 Intel or PPC
        * Xcode 3.1.4
        * ``MacOSX10.5`` SDK
        * ``MACOSX_DEPLOYMENT_TARGET=10.5``
        * Apple ``gcc-4.2``
        * bootstrap non-framework Python 2.7 for documentation build with
          Sphinx (as of 3.4.1)

    - alternate build environments:

        * Mac OS X 10.6.8 with Xcode 3.2.6
            - need to change ``/System/Library/Frameworks/{Tcl,Tk}.framework/Version/Current`` to ``8.4``
        * Note Xcode 4.* does not support building for PPC so cannot be used for this build

2.  64-bit / 32-bit, x86_64 and i386 universal, for OS X 10.6 (and later)::

        /path/to/bootstrap/python2.7 build-installer.py \
            --sdk-path=/Developer/SDKs/MacOSX10.6.sdk \
            --universal-archs=intel \
            --dep-target=10.6

    - builds the following third-party libraries

        * NCurses 5.9 (http://bugs.python.org/issue15037)
        * SQLite 3.8.11
        * XZ 5.0.5

    - uses system-supplied versions of third-party libraries

        * readline module links with Apple BSD editline (libedit)

    - requires ActiveState Tcl/Tk 8.5.15.1 (or later) to be installed for building

    - recommended build environment:

        * Mac OS X 10.6.8 (or later)
        * Xcode 3.2.6
        * ``MacOSX10.6`` SDK
        * ``MACOSX_DEPLOYMENT_TARGET=10.6``
        * Apple ``gcc-4.2``
        * bootstrap non-framework Python 2.7 for documentation build with
          Sphinx (as of 3.4.1)

    - alternate build environments:

        * none.  Xcode 4.x currently supplies two C compilers.
          ``llvm-gcc-4.2.1`` has been found to miscompile Python 3.3.x and
          produce a non-functional Python executable.  As it appears to be
          considered a migration aid by Apple and is not likely to be fixed,
          its use should be avoided.  The other compiler, ``clang``, has been
          undergoing rapid development.  While it appears to have become
          production-ready in the most recent Xcode 5 releases, the versions
          available on the deprecated Xcode 4.x for 10.6 were early releases
          and did not receive the level of exposure in production environments
          that the Xcode 3 gcc-4.2 compiler has had.


*   For Python 2.7.x and 3.2.x, the 32-bit-only installer was configured to
    support Mac OS X 10.3.9 through (at least) 10.6.  Because it is
    believed that there are few systems still running OS X 10.3 or 10.4
    and because it has become increasingly difficult to test and
    support the differences in these earlier systems, as of Python 3.3.0 the PSF
    32-bit installer no longer supports them.  For reference in building such
    an installer yourself, the details are::

        /usr/bin/python build-installer.py \
            --sdk-path=/Developer/SDKs/MacOSX10.4u.sdk \
            --universal-archs=32-bit \
            --dep-target=10.3

    - builds the following third-party libraries

        * Bzip2
        * NCurses
        * GNU Readline (GPL)
        * SQLite 3
        * XZ
        * Zlib 1.2.3
        * Oracle Sleepycat DB 4.8 (Python 2.x only)

    - requires ActiveState ``Tcl/Tk 8.4`` (currently 8.4.20) to be installed for building

    - recommended build environment:

        * Mac OS X 10.5.8 PPC or Intel
        * Xcode 3.1.4 (or later)
        * ``MacOSX10.4u`` SDK (later SDKs do not support PPC G3 processors)
        * ``MACOSX_DEPLOYMENT_TARGET=10.3``
        * Apple ``gcc-4.0``
        * system Python 2.5 for documentation build with Sphinx

    - alternate build environments:

        * Mac OS X 10.6.8 with Xcode 3.2.6
            - need to change ``/System/Library/Frameworks/{Tcl,Tk}.framework/Version/Current`` to ``8.4``


General Prerequisites
---------------------

* No Fink (in ``/sw``) or MacPorts (in ``/opt/local``) or other local
  libraries or utilities (in ``/usr/local``) as they could
  interfere with the build.

* The documentation for the release is built using Sphinx
  because it is included in the installer.  For 2.7.x and 3.x.x up to and
  including 3.4.0, the ``Doc/Makefile`` uses ``svn`` to download repos of
  ``Sphinx`` and its dependencies.  Beginning with 3.4.1, the ``Doc/Makefile``
  assumes there is an externally-provided ``sphinx-build`` and requires at
  least Python 2.6 to run.  Because of this, it is no longer possible to
  build a 3.4.1 or later installer on OS X 10.5 using the Apple-supplied
  Python 2.5.

* It is safest to start each variant build with an empty source directory
  populated with a fresh copy of the untarred source.

* It is recommended that you remove any existing installed version of the
  Python being built::

      sudo rm -rf /Library/Frameworks/Python.framework/Versions/n.n


The Recipe
----------

Here are the steps you need to follow to build a Python installer:

* Run ``build-installer.py``. Optionally you can pass a number of arguments
  to specify locations of various files. Please see the top of
  ``build-installer.py`` for its usage.

  Running this script takes some time, it will not only build Python itself
  but also some 3th-party libraries that are needed for extensions.

* When done the script will tell you where the DMG image is (by default
  somewhere in ``/tmp/_py``).

Building other universal installers
...................................

It is also possible to build a 4-way universal installer that runs on
OS X 10.5 Leopard or later::

    /usr/bin/python /build-installer.py \
        --dep-target=10.5
        --universal-archs=all
        --sdk-path=/Developer/SDKs/MacOSX10.5.sdk

This requires that the deployment target is 10.5, and hence
also that you are building on at least OS X 10.5.  4-way includes
``i386``, ``x86_64``, ``ppc``, and ``ppc64`` (G5).  ``ppc64`` executable
variants can only be run on G5 machines running 10.5.  Note that,
while OS X 10.6 is only supported on Intel-based machines, it is possible
to run ``ppc`` (32-bit) executables unmodified thanks to the Rosetta ppc
emulation in OS X 10.5 and 10.6.  The 4-way installer variant must be
built with Xcode 3.  It is not regularly built or tested.

Other ``--universal-archs`` options are ``64-bit`` (``x86_64``, ``ppc64``),
and ``3-way`` (``ppc``, ``i386``, ``x86_64``).  None of these options
are regularly exercised; use at your own risk.


Testing
-------

Ideally, the resulting binaries should be installed and the test suite run
on all supported OS X releases and architectures.  As a practical matter,
that is generally not possible.  At a minimum, variant 1 should be run on
a PPC G4 system with OS X 10.5 and at least one Intel system running OS X
10.9, 10.8, 10.7, 10.6, or 10.5.  Variant 2 should be run on 10.9, 10.8,
10.7, and 10.6 systems in both 32-bit and 64-bit modes.::

    /usr/local/bin/pythonn.n -m test -w -u all,-largefile
    /usr/local/bin/pythonn.n-32 -m test -w -u all

Certain tests will be skipped and some cause the interpreter to fail
which will likely generate ``Python quit unexpectedly`` alert messages
to be generated at several points during a test run.  These are normal
during testing and can be ignored.

It is also recommend to launch IDLE and verify that it is at least
functional.  Double-click on the IDLE app icon in ``/Applications/Python n.n``.
It should also be tested from the command line::

    /usr/local/bin/idlen.n