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6 Creating Built Distributions

A ``built distribution'' is what you're probably used to thinking of either as a ``binary package'' or an ``installer'' (depending on your background). It's not necessarily binary, though, because it might contain only Python source code and/or byte-code; and we don't call it a package, because that word is already spoken for in Python. (And ``installer'' is a term specific to the Windows world. ** do Mac people use it? **)

A built distribution is how you make life as easy as possible for installers of your module distribution: for users of RPM-based Linux systems, it's a binary RPM; for Windows users, it's an executable installer; for Debian-based Linux users, it's a Debian package; and so forth. Obviously, no one person will be able to create built distributions for every platform under the sun, so the Distutils is designed to enable module developers to concentrate on their specialty--writing code and creating source distributions--while an intermediary species of packager springs up to turn source distributions into built distributions for as many platforms as there are packagers.

Of course, the module developer could be his own packager; or the packager could be a volunteer ``out there'' somewhere who has access to a platform which the original developer does not; or it could be software periodically grabbing new source distributions and turning them into built distributions for as many platforms as the software has access to. Regardless of the nature of the beast, a packager uses the setup script and the `bdist` command family to generate built distributions.

As a simple example, if I run the following command in the Distutils source tree:

      python setup.py bdist

then the Distutils builds my module distribution (the Distutils itself in this case), does a ``fake'' installation (also in the build directory), and creates the default type of built distribution for my platform. Currently, the default format for built distributions is a ``dumb'' archive--tarball on Unix, ZIP file on Windows. (These are called ``dumb'' built distributions, because they must be unpacked in a specific location to work.)

Thus, the above command on a Unix system creates Distutils-0.9.1.plat.tar.gz; unpacking this tarball from the root of the filesystemq installs the Distutils just as though you had downloaded the source distribution and run `python setup.py install`. (Assuming that the target system has their Python installation laid out the same as you do--another reason these are called ``dumb'' distributions.) Obviously, for pure Python distributions, this isn't a huge win--but for non-pure distributions, which include extensions that would need to be compiled, it can mean the difference between someone being able to use your extensions or not.

** filenames are inaccurate here! **

The `bdist` command has a --format option, similar to the `sdist` command, which you can use to select the types of built distribution to generate: for example,

      python setup.py bdist --format=zip

would, when run on a Unix system, create Distutils-0.8.plat.zip--again, this archive would be unpacked from the root directory to install the Distutils.

The available formats for built distributions are:

Format | Description | Notes
--- | --- | ---
zip | zip file (.zip) |
gztar | gzipped tar file (.tar.gz) | (1)
ztar | compressed tar file (.tar.Z) |
tar | tar file (.tar) |
rpm | RPM |
srpm | source RPM | ** to do! **
wininst | self-extracting ZIP file for Windows | (2)

Notes:

(1)
  default on Unix
(2)
  default on Windows ** to-do! **

You don't have to use the `bdist` command with the --formats option; you can also use the command that directly implements the format you're interested in. Some of these `bdist` ``sub-commands'' actually generate several similar formats; for instance, the `bdist_dumb` command generates all the ``dumb'' archive formats (`tar`, `ztar`, `gztar`, and `zip`), and `bdist_rpm` generates both binary and source RPMs. The `bdist` sub-commands, and the formats generated by each, are:

Command | Formats
--- | ---
bdist_dumb | tar, ztar, gztar, zip
bdist_rpm | rpm, srpm
bdist_wininst | wininst