[Distutils] Distutils 1.0.1 releasee

Greg Ward gward@python.net
Fri Nov 10 22:32:05 2000

[Bastian's approach to writing config data]
> class MyDistribution(Distribution):
>     def __init__(self, attrs=None):
>         Distribution.__init__(self, attrs=attrs)
>         self.config_file = self.get_name()+"Conf.py"
>     def create_conf_file(self, directory, data=[]):
>         """generate a configuration file with all metadata the data
>            supplied in the 'data' argument"""
>         data.insert(0, "# this file is automatically created by setup.py")
>         filename = os.path.join(directory, self.config_file)
>         # add metadata
>         metanames = dir(self.metadata) + \
>                     ['fullname', 'contact', 'contact_email']
>         for name in metanames:
>               method = "get_" + name
>               cmd = "%s = %s" % (name, `getattr(self.metadata, method)()`)
>               data.append(cmd)
>         util.execute(write_file, (filename, data),
>           "creating %s" % filename, self.verbose>=1,self.dry_run)
> So create_conf_file generates a file <package>Conf.py. You can call the
> function from any place in your code (or you can call it never).
> I call in two places:
> 1) If I need to store some configuration values, my custom
>    "config" command creates this file with the config values in the
>    'data' list.
> 2) When installing. This way the <package>Conf.py is installed as a
>    module and my program has runtime information by importing the module.

OK, I think I see what you're getting at here.  The fact that
participation is voluntary seems nice at first, but doing it that way
fails to guarantee a standard way to figure out whether package X is
installed on the current system, and which version of X is installed.

And the fact that it's "completely general", and can be used for any
kind of configuration info, also seems nice at first.  But I still think
that's wrong: distribution meta-data (name, version, files installed) is
different from application configuration data.  I think the difference
boils down to this: meta-data is fixed, both determined and interpreted
by the Distutils, while application config data is (by definition!)
entirely application-dependent.  The major corollary of this is that
end-users might edit application config data, but they had bloody well
better not edit installation meta-data.  This alone is sufficient
justification for keeping them rigidly separated.

Also, I *still* don't like Python as a configuration language.  It just
seems wrong, despite the obvious simplicity of

  ADMIN_EMAIL = "gward@python.net"
  FAVOURITE_COLOUR = "greenish-blue"

as a config file.

I think I'll write up a proposal for storing distribution meta-data.
Been mulling it over for long enough, time to write something down.

Connected to but independent of this is the need for a standard way to
specify, install, and find application-dependent configuration data.
The first two are obviously the Distutils' domain; I don't think
applications should be dependent on the Distutils at run-time, but we
can certainly provide sample code, and make the standard installation
location simple and easy so that the boilerplate code to find
application config data is simple and easy.

Greg Ward - programmer-at-large                         gward@python.net
God made machine language; all the rest is the work of man.