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(python2.1-ext.info)Building C and C++ Extensions on UNIX

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Building C and C++ Extensions on UNIX
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This manual section was written by Jim Fulton <jim@Digicool.com>.
Starting in Python 1.4, Python provides a special make file for
building make files for building dynamically-linked extensions and
custom interpreters.  The make file make file builds a make file that
reflects various system variables determined by configure when the
Python interpreter was built, so people building module's don't have to
resupply these settings.  This vastly simplifies the process of
building extensions and custom interpreters on Unix systems.

The make file make file is distributed as the file
`Misc/Makefile.pre.in' in the Python source distribution.  The first
step in building extensions or custom interpreters is to copy this make
file to a development directory containing extension module source.

The make file make file, `Makefile.pre.in' uses metadata provided in a
file named `Setup'.  The format of the `Setup' file is the same as the
`Setup' (or `Setup.dist') file provided in the `Modules/' directory of
the Python source distribution.  The `Setup' file contains variable
definitions:

     EC=/projects/ExtensionClass

and module description lines.  It can also contain blank lines and
comment lines that start with `#'.

A module description line includes a module name, source files,
options, variable references, and other input files, such as libraries
or object files.  Consider a simple example:

     ExtensionClass ExtensionClass.c

This is the simplest form of a module definition line.  It defines a
module, `ExtensionClass', which has a single source file,
`ExtensionClass.c'.

This slightly more complex example uses an *-I* option to specify an
include directory:

     EC=/projects/ExtensionClass
     cPersistence cPersistence.c -I$(EC)

This example also illustrates the format for variable references.

For systems that support dynamic linking, the `Setup' file should begin:

     *shared*

to indicate that the modules defined in `Setup' are to be built as
dynamically linked modules.  A line containing only `*static*' can be
used to indicate the subsequently listed modules should be statically
linked.

Here is a complete `Setup' file for building a `cPersistent' module:

     # Set-up file to build the cPersistence module.
     # Note that the text should begin in the first column.
     *shared*
     
     # We need the path to the directory containing the ExtensionClass
     # include file.
     EC=/projects/ExtensionClass
     cPersistence cPersistence.c -I$(EC)

After the `Setup' file has been created, `Makefile.pre.in' is run with
the `boot' target to create a make file:

     make -f Makefile.pre.in boot

This creates the file, Makefile.  To build the extensions, simply run
the created make file:

     make

It's not necessary to re-run `Makefile.pre.in' if the `Setup' file is
changed.  The make file automatically rebuilds itself if the `Setup'
file changes.

Building Custom Interpreters

Module Definition Options

Example

Distributing your extension modules