Gabriel Genellina wrote:
En Mon, 12 Oct 2009 15:24:34 -0300, Buck <workithar...@gmail.com>
escribió:
On Oct 10, 9:44 am, "Gabriel Genellina" <gagsl-...@yahoo.com.ar>
wrote:
The good thing is that, if the backend package is properly installed
somewhere in the Python path ... it still works with no modifications.
I'd like to get to zero-installation if possible. It's easy with
simple python scripts, why not packages too? I know the technical
reasons, but I haven't heard any practical reasons.
If the reasons are purely technical, it smells like a PEP to me.
That's what I meant to say. It IS a zero-installation schema, and it
also works if you properly install the package. 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).
please don't get angry,
I'm not a programmer, I'm just a human ;-)
Hierarchical choices are done on todays knowledge, tomorrow we might
have different views and want/need to arrange things in another way.
An otter may become a reptile ;-)
So from the human viewpoint the following should be possible (and is for
example possible in Delphi)
- I can move the complete project anywhere I like and it should still
work without any modifications (when I move my desk I can still do my work)
- I can move any file in he project to any other place in the project
and again everything should work without any modifications ( when I
rearrange my books, I can still find a specific book)
In my humble opinion if these actions are not possible, there must be
redundant information in the collection. The only valid reason for
redundant information is to perform self healing (or call it error
correction), and here we have a catch-22.
cheers,
Stef Mientki
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