generate a config.py file at install time

[Paolo Borelli]

It would be nice if we could generate a config.py file at install time when the install prefix is known, the goald would be to avoid code like the one pasted below and make installation in custom prefixes (like the one used by jhbuild) work out of the box without having to manually set env vars for every application.

We already do something like that in gedit-plugins, but it is an autotools based project http://git.gnome.org/browse/gedit-plugins/tree/plugins/gpdefs.py.in

# Detect if we are running from the source dir
if os.path.exists("gnome-clocks.doap"):
    ENV_PATHS = {
        "GNOME_CLOCKS_DATA_PATH": "data/",
        "GNOME_CLOCKS_IMAGE_PATH": "data/",
        "GNOME_CLOCKS_LOCALE_PATH": "locale/",
    }
else:
    ENV_PATHS = {
        "GNOME_CLOCKS_DATA_PATH": "/usr/share/gnome-clocks/",
        "GNOME_CLOCKS_IMAGE_PATH": "/usr/share/gnome-clocks/pixmaps/",
        "GNOME_CLOCKS_LOCALE_PATH": "/usr/share/locale/",
    }

for var, path in ENV_PATHS.iteritems():
    os.environ.setdefault(var, path)