En Tue, 13 Oct 2009 13:28:05 -0300, Buck <workithar...@gmail.com> escribió:
On Oct 12, 3:34 pm, "Gabriel Genellina" <gagsl-...@yahoo.com.ar>
wrote:
Quoting Steven D'Aprano
(changing names slightly):
"""You would benefit greatly from separating the interface from
the backend. You should arrange matters so that the users see something
like this:
project/
+-- animal
+-- mammal
+-- reptile
+-- somepackagename/
+-- __init__.py
+-- animals.py
+-- mammals/
+-- __init__.py
+-- horse.py
+-- otter.py
+-- reptiles/
+-- __init__.py
+-- gator.py
+-- newt.py
+-- misc/
+-- __init__.py
+-- lungs.py
+-- swimming.py
where the front end is made up of three scripts "animal", "mammal" and
"reptile", and the entire backend is in a package.""" [ignore the rest]
By example, the `animal` script would contain:
from somepackagename import animals
animals.main()
or perhaps something more elaborate, but in any case, the script
imports
whatever it needs from the `somepackagename` package.
The above script can be run:
a) directly from the `project` directory; this could be a checked out
copy
from svn, or a tar file extracted in /tmp, or whatever. No need to
install
anything, it just works.
b) alternatively, you may install somepackagename into site-packages
(or
the user site directory, or any other location along the Python path),
and
copy the scripts into /usr/bin (or any other location along the system
PATH), and it still works.
The key is to put all the core functionality into a package, and place
the
package where Python can find it. Also, it's a good idea to use
relative
imports from inside the package. There is no need to juggle with
sys.path
nor even set PYTHONPATH nor import __main__ nor play any strange games;
it
Just Works (tm).
As in the OP, when I have 50 different runnable scripts, it become
necessary to arrange them in directories. How would you do that in
your scheme? Currently it looks like they're required to live directly
above the package containing their code.
I'd say that, if your application contains 50 different runnable scripts
in several directories, it deserves an install script. Being able to
execute something from a checked-out copy is fine for a small application
but in your case I'd say we are off limits...
Python must be able to import the package. In case a) above, this happens
because the directory containing the script (and the package) is in
sys.path by default. In case b), because you copy the package into some
place that is already in sys.path. There is another option: add the
directory containing the package to sys.path, by setting the environment
variable PYTHONPATH. Robert Kern already explained how to do that:
<http://permalink.gmane.org/gmane.comp.python.general/639964>
--
Gabriel Genellina
--
http://mail.python.org/mailman/listinfo/python-list
