cpython/Mac/Demo/building.html

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<H1>Building Mac Python from source</H1>
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This document explains how to build MacPython from source. This is
necessary if you want to write extension modules for 68K Python, and
currently also probably the easiest way to build PPC extension
modules. Building Python is not something to be undertaken lightly,
the process is not very streamlined so you need a reasonable working
knowledge of the CodeWarrior development environment, a good net
connection and probably quite some time too. <p>

The information density in this file is high, so you should probably
print it and read it at your leasure. Most things are explained only
once (and probably in the wrong place:-). <p>

I am very interested in feedback on this document, contact me at <A
HREF="mailto:jack@cwi.nl">&lt;jack@cwi.nl&gt;</A> or send your
comments to the <A
HREF="http://www.python.org/sigs/pythonmac-sig/">Mac Python Special
Interest Group</A>.

<H2>What you need.</H2>

The following things you definitely need:

<UL>

<LI> You need a MacPython source distribution, of course. You can
obtain one from <A
HREF="ftp://ftp.cwi.nl/pub/jack/python/mac">ftp://ftp.cwi.nl/pub/jack/python/mac</A>
or from the companion webpage at <A HREF="http://www.cwi.nl/~jack/macpython.html">
http://www.cwi.nl/~jack/macpython.html</A> (which has up-to-date links to the other
packages needed too)
and possibly also from the standard <A
HREF="ftp://ftp.python.org/pub/python/mac">python.org ftp
site</A>. Everything you need is also included in the standard Python
source distribution, but the organization is different. Look in
directory <code>Mac/mwerks/projects</code> for the project files and
related stuff.

<LI> You need MetroWerks CodeWarrior. The current distribution has
been built with CodeWarrior Pro 2. Ordering information is
available on the <A HREF="http://www.metrowerks.com/">MetroWerks
homepage</A>. Building Python with MPW or Think/Symantec C is
probably impossible without major surgery.

<LI> You need GUSI, the Grand Unified Socket Interface, by Matthias
Neeracher. The original CWGUSI is
obtainable from <A
HREF="ftp://sunsite.cnlab-switch.ch/software/platform/macos/src">
ftp://sunsite.cnlab-switch.ch/software/platform/macos/src</A>.
At the moment Python is built with a slightly modified version of GUSI,
these modifications are available in folder <code>Python:Mac:GUSI-mods</code>.

</UL>

<A NAME="optional">The MacPython project files are configured to
include a plethora of optional modules</A>, and these modules need a
number of extra packages. To use the project files as-is you have to
download these packages too. PPC and CFM68K Python have all such modules as
dynamically loaded modules, so if you don't need a certain package it
suffices to just refrain from builing the extension module. For static 68K
Python things are a bit more complicated: you have to edit the
interpreter project file to remove the reference to the module (and
the libraries it uses), and edit the <code>Mac:mwerks:mwerks_nonshared_config.h</code>
file to remove the <code>USE_...</code> line.  Here are the locations for the various things
you need:

<UL>

<LI> Tcl and Tk can be obtained from <A
HREF="ftp://ftp.smli.com/pub/tcl/mac/">ftp://ftp.smli.com/pub/tcl/mac/</A>.
The current distributions, Tcl 8.0p2 and Tk 8.0p2 need a bit of work,
see the section on <A HREF="#tcltk">building Tcl/Tk Python</A>
below. Get the "full source" distribution, which includes MoreFiles.

<LI> Waste, a TextEdit replacement written by Marco Piovanelli, <A
HREF="mailto:piovanel@kagi.com">&lt;piovanel@kagi.com&gt;</A>.  Python
was built using version 1.3, which you can obtain from <A
HREF="http://www.boingo.com/waste">&lt;http://www.boingo.com/waste&gt;</A>
and various other places.

<LI> Gdbm library for the Mac. Available from Jack's Mac software page at
<A HREF="http://www.cwi.nl/~jack/macsoftware.html">
http://www.cwi.nl/~jack/macsoftware.html</A> and <A HREF="ftp://ftp.cwi.nl/pub/jack/mac">
ftp://ftp.cwi.nl/pub/jack/mac</A>.

<LI> JPEG library by the Independent JPEG Group. A version including
Mac projects can be found at Jack's page mentioned above. 
The most recent JPEG library can always be obtained from <A
HREF="ftp://ftp.uu.net/graphics/jpeg/">ftp://ftp.uu.net/graphics/jpeg/</A>.

<LI> The netpbm/pbmplus, libtiff, zlib and png libraries. The netpbm distribution
(which includes libtiff) is generally available on Internet ftp
servers. For Python pbmplus, an older incarnation of netpbm, is
functionally identical to netpbm, since Python only uses the library
and not the complete applications. A distribution with correct
projects and library source only is available from, you guessed it, Jack's Mac software
page mentioned above.

</UL>

<H2>Setting Up</H2>

Now that you have collected everything you should start with building
the various parts.  If you don't want to fix
access paths try to set things up as follows:

<PRE>
Top-level-folder:
	CWGUSI
	imglibs
		jpeg
		netpbm
			libtiff
		zlib
		png
	gdbm
	Python
	Tcl/Tk Folder
		tcl8.0
		tk8.0
		MoreFiles 1.4.3
	Waste 1.3 distribution (if you want waste)
</PRE>

If your setup of the libraries is exactly the same as mine (which is
not very likely, unless you happen to work from the same CVS
repository) you can use the project <code>buildlibs.prj</code> in the
<code>build.mac</code> folder to build all needed libraries in one
fell swoop, otherwise you will have to build the libraries one by
one. <p>

First build GUSI. If you didn't get the python-specific GUSI you have to 
move the files from the "CWGUSI-mods" to the right
place in the CWGUSI distribution folder. Build the MSL version for your
platform (ppc, 68k, cfm68k). <p>

Next, in
<code>MoreFiles</code>, <code>libjpeg</code>, <code>pbmplus</code>,
<code>zlib</code>, <code>libpng</code>, <code>gdbm</code>,
and<code>libtiff</code> you build all projects. Usually the projects are in "mac"
subfolders, sometimes they are in the main folder. Tcl/tk is a special
case, see below. Of course, if you are only interested in one of
static 68K, CFM68K or PPC you can skip building the other libraries.

<H2><A NAME="tcltk">Building Tcl/Tk</H2>

You need to make some minor changes to the Tcl/Tk 8.0
distribution. You should make the CW Pro projects (in the mac subfolders).
<UL>

<LI> There are no cfm68k targets. You make these by copying the 68k targets,
setting the "68k target" to "cfm68k library" and changing the output filename,
and changing the prefix
header filename in the C/C++ settings panel to "MW_???HeaderCFM68K".

<LI> I had to add Search.c (from MoreFiles) to the tcl library projects. I don't
understand why this is, but it seemed to cure the problems I had.

<LI> Note that if you use a different release of Tcl and Tk than the ones
I have used you may have to adapt the Python <code>tkresources.rsrc</code> file.
This is easiest done by building <code>SimpleTk</code> and copying the TEXT, ICON
and CRSR resources from it to <code>tkresources.rsrc</code>. This allows
the <code>_tkinter</code> module to work without an installed Tk/Tcl on your
machine.

</UL>

Build first the Tcl library, then
SimpleTcl (test it by typing <code>ls -l</code> in the window you get)
then the Tk library, then SimpleTk (which can again be tested with
<code>ls -l</code>). If this all worked you are all set to try
building Python.

<H2>Building Waste</H2>

You do not need to build the Waste libraries, as Python includes the
source modules themselves.

<H2>The organization of the Python source tree</H2>

Time for a short break, while we have a look at the organization of
the Python source tree.  At the top level, we find the following
folders:

<DL>
<DT> build.macstand
<DD> This is where you build static 68K interpreter, and possibly (if
you want them) static PPC and fat interpreters. There is also a project
here that builds smaller versions of the static interpreter.

<DT> build.mac
<DD> This is where you build the CFM68K, PPC and fat shared library,
interpreter and applet framework. The fat targets are deposited in the
main folder (one level up), the others, which are intermediate results
really, are left here.

<DT> Demo
<DD> Demo programs that are not Mac-specific. Some of these may not
work, the file <code>README-Mac</code> has some details.

<DT> Extensions
<DD> Extensions to the interpreter that are not Mac-specific. Contains
only the <code>img</code> extension in this distribution. Extensions
are not always built here, as they are on Unix, but sometimes incorporated in
the core interpreter or built as plugin modules.

<DT> Grammar
<DD> The Python grammar. Included for reference only, you cannot build
the parser on a Mac.

<DT> Include
<DD> Machine-independent header files.

<DT> Modules
<DD> Machine-independent optional modules. Not all of these will work
on the Mac.

<DT> Objects
<DD> Machine-independent code for various objects. Most of these are
not really optional: the interpreter will not function without them.

<DT> Parser
<DD> The Python parser (machine-independent).

<DT> PlugIns
<DD> This is where you build the PPC and CFM68K dynamically-loaded plugin modules.

<DT> Python
<DD> The core interpreter. Most files are machine-independent, some
are unix-specific and not used on the Mac.

<DT> Tools
<DD> Tools for python developers. Contains <code>modulator</code>
which builds skeleton C extension modules and <code>bgen</code> which
generates complete interface modules from information in C header
files. There are some readme files, but more documentation is sorely
needed.

</DL>

All the mac-specific stuff lives in the <code>Mac</code> folder:
<DL>

<DT> Compat
<DD> Unix-compatability routines. Some of these are not used anymore,
since CWGUSI provides a rather complete emulation, but you may need
these if you are trying to build a non-GUSI python.

<DT> Demo
<DD> Mac-specific demo programs, some of them annotated.

<DT> Include
<DD> Mac-specific but compiler-independent include files. 

<DT> Lib
<DD> Mac-specific standard modules. The <code>toolbox</code> folder
contains modules specifically needed with various MacOS toolbox
interface modules.

<DT> Modules
<DD> Mac-specific builtin modules. Theoretically these are all
optional, but some are rather essential (like
<code>macmodule</code>). A lot of these modules are generated with
<code>bgen</code>, in which case the bgen input files are included so
you can attempt to regenerate them or extend them.

<DT> MPW
<DD> MPW-specific files. These have not been used or kept up-to-date
for a long time, so use at your own risk.

<DT> mwerks
<DD> Mwerks-specific sources and headers. Contains glue code for
Pythons shared-library architecture, a replacement for
<code>malloc</code> and a directory with various projects for building
variations on the Python interpreter. The <code>mwerks_*.h</code>
files here are the option-setting files for the various interpreters
and such, comparable to the unix command-line <code>-D</code> options
to the compiler. Each project uses the correct option file as its
"prefix file" in the "C/C++ language" settings. Disabling optional
modules (for the 68K interpreter), building non-GUSI interpreters and
various other things are accomplished by modifying these files (and
possibly changing the list of files included in the project window, of
course).

<DT> Python
<DD> Mac-specific parts of the core interpreter.

<DT> Resources
<DD> Resource files needed to build the interpreter.

<DT> Scripts
<DD> A collection of various mac-specific Python scripts. Some are
essential, some are useful but few are documented, so you will have to
use your imagination to work them out.

<DT> Unsupported
<DD> Modules that are not supported any longer but may still work with a little effort.
</DL>

<H2>Building the 68K interpreter</H2>

If you have all the optional libraries mentioned <A
HREF="#optional">above</A> loaded buildin Python for 68K macs is a
breeze: open the project in the folder <code>build.macstand</code> and
build the 68K target.  Do <em>not</em> run it yet, this will possibly
result in a garbled preferences file. <p>

First remove the <code>Python XXX preferences</code> file from your
preference folder, only if you had an older version of Python
installed.  (this is also what you do if you did not heed the last
sentence of the preceeding paragraph). Next, move the interpreter to
the main Python folder (up one level) and run it there. This will
create a correct initial preferences file. You are now all set, and
your tree should be completely compatible with a binary-only
distribution. Read the release notes
(<code>Relnotes-somethingorother</code>) and
<code>ReadMe</code> in the <code>Mac</code> folder.

<H2>Building the PPC and CFM68K interpreter</H2>

First you build the interpreter, core library and applet skeleton in
folder <code>build.mac</code>. The projects are all linked together, so
building the fat targets in <code>Python.prj</code> and
<code>PythonApplet.prj</code> will result in everything being built. The
resulting applications and fat shared library are deposited in the main
Python folder. For completeness sake here is a breakdown of the
projects:

<DL>

<DT> PythonCore (with subprojects PythonCorePPC and PythonCoreCFM68K)
<DD> The shared library that contains the bulk of the interpreter and
its resources. It is a good idea to immedeately put an alias to this
shared library in the <code>Extensions</code> folder of your system
folder.  Do exactly that: put an <em>alias</em> there, copying or
moving the file will cause you grief later if you rebuild the library and
forget to copy it to the extensions folder again.

<DT> Python
<DD> The interpreter. This is basically a routine to call out to the
shared library.  <p>

<DT> PythonAppletPPC
<DD> The applet skeleton application. Very similar to
<code>PythonPPC</code>, but it calls to a different entrypoint in the
core library. The <code>mkapplet</code> script will copy this complete
file, and add a <code>'PYC '</code> with the module to generate an
applet. <p>

</DL>

After creating the alias to <code>PythonCore</code> you remove any old
<code>Python XXX Preferences</code> file from the <code>Preferences</code> folder
(if you had python installed on your system before) and run the interpreter once
to create the correct preferences file.  <p>

Next, you have to build the extension modules in the
<code>PlugIns</code> folder. The <code>PlugIns.ppc</code> project has all the
other projects as subprojects and builds everything. After all
the dynamically loaded modules are built you have to create a number
of aliases: some modules live together in a single dynamic
library. Run the <code>ConfigurePython.py</code> script from
<code>Mac:scripts</code> to create the aliases. <p>

Finally, you must build the standard applets:
<code>EditPythonPrefs</code>, <code>BuildApplet</code>, etc. This is
easiest done with the <code>fullbuild</code> script from
<code>Mac:scripts</code>. <p>

<BLOCKQUOTE>
Actually, the <code>fullbuild</code> script can be used to build
everything, but you need a fully-functional interpreter before you can
use it (and one that isn't rebuilt in the process: you cannot rebuild
a running program). You could copy the 68K interpreter to a different
place and use that to run fullbuild, or use the standalone PPC python
for this. I tend to keep a standalone interpreter in a safe place for
this use only. <p>

</BLOCKQUOTE>

You are all set now, and should read the release notes and
<code>ReadMe</code> file from the <code>Mac</code> folder.

<H2>Rebuilding <code>.exp</code> files for PPC and CFM68K</H2>

Occasionally it may be necessary to rebuild your PythonCore <code>.exp</code>
file, a file that controls which symbols are exported by your PythonCore
shared library. Rebuild it if you get unexpected undefined symbols when you
are building a plugin module. <p>

Rebuilding the .exp file is done by first removing the file and removing the
reference to it in the project (in the "config" section). Next, build PythonCore.
This will create a new .exp file. Edit this file to remove the references to
the symbols <code>__initialize</code>, <code>__terminate</code>, <code>setjmp</code>,
<code>longjmp</code>, <code>main</code> and (for PPC) <code>__ptmf_null</code> or (for
CFM68K) <code>__start</code> and <code>dummy_init_routine</code>.
Next, add the .exp file to the project
again and rebuild PythonCore. <p>

This rather convoluted procedure is needed to ensure that plugin modules don't
accidentally link with those entrypoints from PythonCore, which will not work because
those routines have to be in the same code fragment as they are used from.

<H2>Odds and ends</H2>

Some remarks that I could not fit in elsewhere:

<UL>

<LI> It may be possible to use the <code>PythonCore</code> shared
library to embed Python in another program, if your program can live
with using GUSI for I/O. Use PythonCore in stead of your MSL C library
(or, at the very least, link it before the normal C library). Let me
know whether this works.

<LI> It is possible to build PPC extension modules without building a
complete Python. Take the binary distribution, add folders
<code>Include</code>, <code>Mac:Include</code> and
<code>Mac:mwerks</code> from the source distribution and you should be
all set. A template for a dynamic module can be found in
<code>xx.prj</code>.

<LI> The Python shared library architecture is a variant of the architecture
described as "application with shared libraries and dropins" in the MetroWerks
"Targeting MacOS" documentation. The Python Application and applet-template use
the <code>MSL AppRuntime.Lib</code> runtime library (with properly set CFM
initialization and termination routines). PythonCore uses <code>MSL Runtime.Lib</code>,
which is really intended for standalone programs but which we fool into working by
providing a dummy main program.
It is linked statically into PythonCore (and exported to the applications and plugins)
so we do not have to distribute yet another shared library. Plugin modules use
<code>MSL ShlibRuntime.Lib</code> (not the dropin runtime: modules are never unloaded)
and obtain the rest from PythonCore. PythonCore uses a
non-standard initialization entry point, <code>__initialize_with_resources</code>, to
be able to obtain resources from the library file later on. Plugins can do the same
(_tkinter does) or use the standard <code>__initialize</code> entry point.


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