=========================

Python on Mac OS X README

=========================

:Authors:

Jack Jansen (2004-07),

Ronald Oussoren (2010-04),

Ned Deily (2012-06)

:Version: 3.4.0

This document provides a quick overview of some Mac OS X specific features in

the Python distribution.

OS X specific arguments to configure

====================================

* ``--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 is 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 OS X SDK should be used to perform the

build. If xcodebuild is available and configured, this defaults to

the Xcode default MacOS X SDK, otherwise ``/Developer/SDKs/MacOSX.10.4u.sdk``

if available or ``/`` if not. When building on OS X 10.5 or later, you can

specify ``/`` to use the installed system headers rather than an SDK. As of

OS X 10.9, you should install the optional system headers from the Command

Line Tools component using ``xcode-select``::

$ sudo xcode-select --install

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

for more information.

* ``--with-universal-archs=VALUE``

Specify the kind of universal binary that should be created. This option is

only valid when ``--enable-universalsdk`` is specified. The default is

``32-bit`` if a building with a SDK that supports PPC, otherwise defaults

to ``intel``.

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 more than one

CPU architecture. A universal OS X executable file or library combines the

architecture-specific code into one file and can therefore run at native

speed on all supported architectures. Universal files were introduced in

OS X 10.4 to add support for Intel-based Macs to the existing PowerPC (PPC)

machines. In OS X 10.5 support was extended to 64-bit Intel and 64-bit PPC

architectures. It is possible to build Python with various combinations

of architectures depending on the build tools and OS X version in use.

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. Universal builds were first supported with OS X 10.4 with Xcode 2.1

and the 10.4u SDK. Starting with Xcode 3 and OS X 10.5, more configurations are

available.

In general, universal builds depend on specific features provided by the

Apple-supplied compilers and other build tools included in Apple's Xcode

development tools. You should install Xcode and the command line tools

component appropriate for the OS X release you are running on. See the

Python Developer's Guide (https://devguide.python.org/setup/)

for more information.

2.1 Flavors of universal binaries

.................................

It is possible to build a number of flavors of the universal binary build,

the default is a 32-bit only binary (i386 and ppc) in build environments that

support ppc (10.4 with Xcode 2, 10.5 and 10.6 with Xcode 3) or an

Intel-32/-64-bit binary (i386 and X86_64) in build environments that do not

support ppc (Xcode 4 on 10.6 and later systems). The flavor can be specified

using the configure option ``--with-universal-archs=VALUE``. The following

values are available:

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

* ``intel-32``: ``i386``

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

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

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

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

To build a universal binary that includes a 64-bit architecture, you must build

on a system running OS X 10.5 or later. The ``all`` and ``64-bit`` flavors can

only be built with a 10.5 SDK because ``ppc64`` support was only included with

OS X 10.5. Although legacy ``ppc`` support was included with Xcode 3 on OS X

10.6, it was removed in Xcode 4, versions of which were released on OS X 10.6

and which is the standard for OS X 10.7. To summarize, the

following combinations of SDKs and universal-archs flavors are available:

* 10.4u SDK with Xcode 2 supports ``32-bit`` only

* 10.5 SDK with Xcode 3.1.x supports all flavors

* 10.6 SDK with Xcode 3.2.x supports ``intel``, ``3-way``, and ``32-bit``

* 10.6 SDK with Xcode 4 supports ``intel`` only

* 10.7 and 10.8 SDKs with Xcode 4 support ``intel`` only

* 10.8 and 10.9 SDKs with Xcode 5 support ``intel`` only

The makefile for a framework build will also install ``python3.4-32``

binaries when the universal architecture includes at least one 32-bit

architecture (that is, for all flavors but ``64-bit``).

Running a specific architecture

...............................

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.

Using ``arch`` is not a perfect solution as the selected architecture will

not automatically carry through to subprocesses launched by programs and tests

under that Python. If you want to ensure that Python interpreters launched in

subprocesses also run in 32-bit-mode if the main interpreter does, use

a ``python3.4-32`` binary and use the value of ``sys.executable`` as the

``subprocess`` ``Popen`` executable value.

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 Mac OS X application bundle (".app").

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/Python <VERSION>" where ``<VERSION>`` can be e.g. "3.4",

"2.7", 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 OS X AquaTk

distribution, this is installed by default on Mac OS X 10.4 or later. Be

aware, though, that the Cocoa-based AquaTk's supplied starting with OS X

10.6 have proven to be unstable. If possible, you should consider

installing a newer version before building on OS X 10.6 or later, such as

the ActiveTcl 8.5. See http://www.python.org/download/mac/tcltk/. If you

are building with an SDK, ensure that the newer Tcl and Tk frameworks are

seen in the SDK's ``Library/Frameworks`` directory; you may need to

manually create symlinks to their installed location, ``/Library/Frameworks``.

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 (full-blown OS X .app applications, that is) in

"/Applications/Python <VERSION>", and a hidden helper application Python.app

inside the Python.framework, and unix tools including "python" 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/Python <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, is possible. This can be accomplished

by configuring with ``--enable-framework=$HOME/Library/Frameworks``.

The other two directories will then also be installed in your home directory,

at ``$HOME/Applications/Python-<VERSION>`` and ``$HOME/bin``.

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/Python <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.

"Python Launcher.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 ``Option`` key depressed while dragging or double-clicking

a script to set runtime options. These options can be set persistently

through Python Launcher's preferences dialog.

The program ``pythonx.x`` runs python scripts from the command line.

Previously, various compatibility aliases were also installed, including

``pythonwx.x`` which in early releases of Python on OS X was required to run

GUI programs. As of 3.4.0, the ``pythonwx.x`` aliases are no longer installed.

How do I create a binary distribution?

======================================

Download and unpack the source release from http://www.python.org/download/.

Go to the directory ``Mac/BuildScript``. There you will 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 also builds an HTML copy of the current Python

documentation set for this release for inclusion in the framework. The

installer package will create links to the documentation for use by IDLE,

pydoc, shell users, and Finder user.

The script will build a universal binary so you'll therefore have to run this

script on Mac OS X 10.4 or later and with Xcode 2.1 or later installed.

However, the Python build process itself has several build dependencies not

available out of the box with OS X 10.4 so you may have to install

additional software beyond what is provided with Xcode 2. OS X 10.5

provides a recent enough system Python (in ``/usr/bin``) to build

the Python documentation set. It should be possible to use SDKs and/or older

versions of Xcode to build installers that are compatible with older systems

on a newer system but this may not be completely foolproof so the resulting

executables, shared libraries, and ``.so`` bundles should be carefully

examined and tested on all supported systems for proper dynamic linking

dependencies. It is safest to build the distribution on a system running the

minimum OS X version supported.

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 libraries 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.

OS X does not provide 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``.

Resources

=========

* http://www.python.org/download/mac/

* http://www.python.org/community/sigs/current/pythonmac-sig/

* https://devguide.python.org/