cpython/Mac

============
MacOSX Notes
============

This document provides a quick overview of some Mac OS X specific features in
the Python distribution.

* ``--enable-framework[=DIR]``

  If this argument is specified the build will create a Python.framework rather
  than a traditional Unix install. See the section
  _`Building and using a framework-based Python on Mac OS X` for more 
  information on frameworks.

  If the optional directory argument is specified the framework it installed
  into that directory. This can be used to install a python framework into
  your home directory::

     $ configure --enable-framework=/Users/ronald/Library/Frameworks
     $ make && make install

  This will install the framework itself in ``/Users/ronald/Library/Frameworks``,
  the applications in a subdirectory of ``/Users/ronald/Applications`` and the
  command-line tools in ``/Users/ronald/bin``.

* ``--with-framework-name=NAME``

  Specify the name for the python framework, defaults to ``Python``. This option
  is only valid when ``--enable-framework`` is specified.

* ``--enable-universalsdk[=PATH]``

  Create a universal binary build of Python. This can be used with both
  regular and framework builds.

  The optional argument specifies which OSX SDK should be used to perform the
  build. This defaults to ``/Developer/SDKs/MacOSX.10.4u.sdk``, specify 
  ``/`` when building on a 10.5 system, especially when building 64-bit code.

  See the section _`Building and using a universal binary of Python on Mac OS X`
  for more information.

* ``--with-univeral-archs=VALUE``

  Specify the kind of universal binary that should be created. This option is 
  only valid when ``--enable-universalsdk`` is specified.


Building and using a universal binary of Python on Mac OS X
===========================================================

1. What is a universal binary
-----------------------------

A universal binary build of Python contains object code for both PPC and i386
and can therefore run at native speed on both classic powerpc based macs and
the newer intel based macs.

2. How do I build a universal binary
------------------------------------

You can enable universal binaries by specifying the "--enable-universalsdk"
flag to configure::

  $ ./configure --enable-universalsdk
  $ make
  $ make install

This flag can be used with a framework build of python, but also with a classic
unix build. Either way you will have to build python on Mac OS X 10.4 (or later)
with Xcode 2.1 (or later). You also have to install the 10.4u SDK when 
installing Xcode.

2.1 Flavours of universal binaries
..................................

It is possible to build a number of flavours of the universal binary build,
the default is a 32-bit only binary (i386 and ppc). The flavour can be
specified using the option ``--with-universal-archs=VALUE``. The following
values are available:

  * ``32-bit``:   ``ppc``, ``i386``

  * ``64-bit``:   ``ppc64``, ``x86_64``

  * ``all``:      ``ppc``, ``ppc64``, ``i386``, ``x86_64``

  * ``3-way``:	  ``ppc``, ``i386`` and ``x86_64``

  * ``intel``:	  ``i386``, ``x86_64``

To build a universal binary that includes a 64-bit architecture, you must build
on a system running OSX 10.5 or later. The ``all`` flavour can only be built on
OSX 10.5.

The makefile for a framework build will install ``python32`` and ``pythonw32`` 
binaries when the universal architecures includes at least one 32-bit architecture
(that is, for all flavours but ``64-bit``).

Running a specific archicture
.............................

You can run code using a specific architecture using the ``arch`` command::

   $ arch -i386 python

Or to explicitly run in 32-bit mode, regardless of the machine hardware::

   $ arch -i386 -ppc python

NOTE: When you're using a framework install of Python this requires at least
Python 2.7 or 3.2, in earlier versions the python (and pythonw) commands are
wrapper tools that execute the real interpreter without ensuring that the
real interpreter runs with the same architecture.

Building and using a framework-based Python on Mac OS X.
========================================================


1. Why would I want a framework Python instead of a normal static Python?
--------------------------------------------------------------------------

The main reason is because you want to create GUI programs in Python. With the
exception of X11/XDarwin-based GUI toolkits all GUI programs need to be run 
from a fullblown MacOSX application (a ".app" bundle).

While it is technically possible to create a .app without using frameworks you
will have to do the work yourself if you really want this.

A second reason for using frameworks is that they put Python-related items in
only two places: "/Library/Framework/Python.framework" and 
"/Applications/MacPython <VERSION>" where ``<VERSION>`` can be e.g. "2.6",
"3.1", etc..  This simplifies matters for users installing 
Python from a binary distribution if they want to get rid of it again. Moreover,
due to the way frameworks work a user without admin privileges can install a 
binary distribution in his or her home directory without recompilation.

2. How does a framework Python differ from a normal static Python?
------------------------------------------------------------------

In everyday use there is no difference, except that things are stored in
a different place. If you look in /Library/Frameworks/Python.framework
you will see lots of relative symlinks, see the Apple documentation for
details. If you are used to a normal unix Python file layout go down to
Versions/Current and you will see the familiar bin and lib directories.

3. Do I need extra packages?
----------------------------

Yes, probably.  If you want Tkinter support you need to get the OSX AquaTk 
distribution, this is installed by default on Mac OS X 10.4 or later. If
you want wxPython you need to get that. If you want Cocoa you need to get
PyObjC. 

4. How do I build a framework Python?
-------------------------------------

This directory contains a Makefile that will create a couple of python-related
applications (fullblown OSX .app applications, that is) in
"/Applications/MacPython <VERSION>", and a hidden helper application Python.app 
inside the Python.framework, and unix tools "python" and "pythonw" into 
/usr/local/bin.  In addition it has a target "installmacsubtree" that installs 
the relevant portions of the Mac subtree into the Python.framework.

It is normally invoked indirectly through the main Makefile, as the last step
in the sequence

 1. ./configure --enable-framework

 2. make
 
 3. make install

This sequence will put the framework in /Library/Framework/Python.framework,
the applications in "/Applications/MacPython <VERSION>" and the unix tools in 
/usr/local/bin.

Installing in another place, for instance $HOME/Library/Frameworks if you have
no admin privileges on your machine, has only been tested very lightly. This
can be done by configuring with --enable-framework=$HOME/Library/Frameworks.
The other two directories, "/Applications/MacPython-<VERSION>" and
/usr/local/bin, will then also be deposited in $HOME. This is sub-optimal for
the unix tools, which you would want in $HOME/bin, but there is no easy way to
fix this right now.

If you want to install some part, but not all, read the main Makefile. The
frameworkinstall is composed of a couple of sub-targets that install the
framework itself, the Mac subtree, the applications and the unix tools.

There is an extra target frameworkinstallextras that is not part of the
normal frameworkinstall which installs the Tools directory into
"/Applications/MacPython <VERSION>", this is useful for binary
distributions.

What do all these programs do?
===============================

"IDLE.app" is an integrated development environment for Python: editor,
debugger, etc.

"PythonLauncher.app" is a helper application that will handle things when you
double-click a .py, .pyc or .pyw file. For the first two it creates a Terminal
window and runs the scripts with the normal command-line Python. For the
latter it runs the script in the Python.app interpreter so the script can do
GUI-things. Keep the "alt" key depressed while dragging or double-clicking a
script to set runtime options. These options can be set once and for all
through PythonLauncher's preferences dialog.

The commandline scripts /usr/local/bin/python and pythonw can be used to run
non-GUI and GUI python scripts from the command line, respectively.

How do I create a binary distribution?
======================================

Go to the directory "Mac/OSX/BuildScript". There you'll find a script 
"build-installer.py" that does all the work. This will download and build
a number of 3rd-party libaries, configures and builds a framework Python,
installs it, creates the installer package files and then packs this in a
DMG image.

The script will build a universal binary, you'll therefore have to run this
script on Mac OS X 10.4 or later and with Xcode 2.1 or later installed.

All of this is normally done completely isolated in /tmp/_py, so it does not
use your normal build directory nor does it install into /.

Because of the way the script locates the files it needs you have to run it
from within the BuildScript directory. The script accepts a number of 
command-line arguments, run it with --help for more information.

Configure warnings
==================

The configure script sometimes emits warnings like the one below::

   configure: WARNING: libintl.h: present but cannot be compiled
   configure: WARNING: libintl.h:     check for missing prerequisite headers?
   configure: WARNING: libintl.h: see the Autoconf documentation
   configure: WARNING: libintl.h:     section "Present But Cannot Be Compiled"
   configure: WARNING: libintl.h: proceeding with the preprocessor's result   
   configure: WARNING: libintl.h: in the future, the compiler will take precedence
   configure: WARNING:     ## -------------------------------------- ##
   configure: WARNING:     ## Report this to http://bugs.python.org/ ##
   configure: WARNING:     ## -------------------------------------- ##

This almost always means you are trying to build a universal binary for
Python and have libaries in ``/usr/local`` that don't contain the required
architectures. Temporarily move ``/usr/local`` aside to finish the build.


Uninstalling a framework install, including the binary installer
================================================================

Uninstalling a framework can be done by manually removing all bits that got installed.
That's true for both installations from source and installations using the binary installer.
Sadly enough OSX does not have a central uninstaller.

The main bit of a framework install is the framework itself, installed in
``/Library/Frameworks/Python.framework``. This can contain multiple versions
of Python, if you want to remove just one version you have to remove the
version-specific subdirectory: ``/Library/Frameworks/Python.framework/Versions/X.Y``.
If you do that, ensure that ``/Library/Frameworks/Python.framework/Versions/Current``
is a symlink that points to an installed version of Python.

A framework install also installs some applications in ``/Applications/Python X.Y``,

And lastly a framework installation installs files in ``/usr/local/bin``, all of
them symbolic links to files in ``/Library/Frameworks/Python.framework/Versions/X.Y/bin``.

Odds and ends
=============

Something to take note of is that the ".rsrc" files in the distribution are
not actually resource files, they're AppleSingle encoded resource files. The
macresource module and the Mac/OSX/Makefile cater for this, and create
".rsrc.df.rsrc" files on the fly that are normal datafork-based resource
files.

	Jack Jansen, Jack.Jansen@cwi.nl, 15-Jul-2004.
	Ronald Oussoren, RonaldOussoren@mac.com, 30-April-2010