cpython/Mac/OSX

Building and using a framework-based Python on Mac OS X.
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This document provides a quick introduction to framework-based Python.
It is rather terse and probably incomplete, please send me feedback.

1. Why would I want a framework Python in stead of a normal static Python?
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The main reason is because you want to create GUI programs in Python. With
the exception of X11/XDarwin-based GUI toolkits it appears that 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/Python.
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?
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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?
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Yes, probably. If you want to be able to use the PythonIDE you will need to
get Waste, an all-singing-all-dancing TextEdit replacement, from www.merzwaren.com.
It will unpack into a folder named something like "Waste 2.1 Distribution". Make
a symlink called "waste" to this folder, somewhere beside your Python source
distribution (it can be "../waste", "../../waste", etc).

If you want Tkinter support you need to get the OSX AquaTk distribution. If you
want wxPython you need to get that. If you want Cocoa you need to get pyobjc.
Because all these are currently in a state of flux please refer to
http://www.cwi.nl/~jack/macpython.html, which should contain pointers to more
information.

4. How do I build a framework Python?
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This directory contains a Makefile that will create a couple of python-related
applications (fullblown OSX .app applications, that is) in /Applications/Python,
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 frameworkinstall

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

Building 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/Python 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.

Note that there are no references to the actual locations in the code or resource
files, so you are free to move things around afterwards. For example, you could
use --enable-framework=/tmp/newversion/Library/Frameworks and use /tmp/newversion
as the basis for an installer or something.

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.

If you want to run the Makefile here directly, in stead of through the main Makefile,
you will have to pass various variable-assignments. Read the beginning of the Makefile
for details.


5. What do all these programs do?
---------------------------------

PythonIDE.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.

BuildApplet.app creates an applet from a Python script. Drop the script on it
and out comes a full-featured MacOS application. There is much more to this, to
be supplied later. Some useful (but outdated) info can be found in Mac/Demo.

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.

6. Odds and ends.
-----------------

The PythonLauncher is actually an Objective C Cocoa app built with Project Builder.
It could be a Python program, except for the fact that pyobjc is not a part of
the core distribution, and is not completely finished yet as of this writing.

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@oratrix.com, 12-Aug-02