What is the best project structure for a Python application?
According to Jean-Paul Calderone's Filesystem structure of a Python project:
Project/
|-- bin/
| |-- project
|
|-- project/
| |-- test/
| | |-- __init__.py
| | |-- test_main.py
| |
| |-- __init__.py
| |-- main.py
|
|-- setup.py
|-- README
This blog post by Jean-Paul Calderone is commonly given as an answer in #python on Freenode.
Filesystem structure of a Python project
Do:
- name the directory something related to your project. For example, if your project is named "Twisted", name the top-level directory for its source files
Twisted
. When you do releases, you should include a version number suffix:Twisted-2.5
.- create a directory
Twisted/bin
and put your executables there, if you have any. Don't give them a.py
extension, even if they are Python source files. Don't put any code in them except an import of and call to a main function defined somewhere else in your projects. (Slight wrinkle: since on Windows, the interpreter is selected by the file extension, your Windows users actually do want the .py extension. So, when you package for Windows, you may want to add it. Unfortunately there's no easy distutils trick that I know of to automate this process. Considering that on POSIX the .py extension is a only a wart, whereas on Windows the lack is an actual bug, if your userbase includes Windows users, you may want to opt to just have the .py extension everywhere.)- If your project is expressable as a single Python source file, then put it into the directory and name it something related to your project. For example,
Twisted/twisted.py
. If you need multiple source files, create a package instead (Twisted/twisted/
, with an emptyTwisted/twisted/__init__.py
) and place your source files in it. For example,Twisted/twisted/internet.py
.- put your unit tests in a sub-package of your package (note - this means that the single Python source file option above was a trick - you always need at least one other file for your unit tests). For example,
Twisted/twisted/test/
. Of course, make it a package withTwisted/twisted/test/__init__.py
. Place tests in files likeTwisted/twisted/test/test_internet.py
.- add
Twisted/README
andTwisted/setup.py
to explain and install your software, respectively, if you're feeling nice.Don't:
- put your source in a directory called
src
orlib
. This makes it hard to run without installing.- put your tests outside of your Python package. This makes it hard to run the tests against an installed version.
- create a package that only has a
__init__.py
and then put all your code into__init__.py
. Just make a module instead of a package, it's simpler.- try to come up with magical hacks to make Python able to import your module or package without having the user add the directory containing it to their import path (either via PYTHONPATH or some other mechanism). You will not correctly handle all cases and users will get angry at you when your software doesn't work in their environment.
Doesn't too much matter. Whatever makes you happy will work. There aren't a lot of silly rules because Python projects can be simple.
/scripts
or/bin
for that kind of command-line interface stuff/tests
for your tests/lib
for your C-language libraries/doc
for most documentation/apidoc
for the Epydoc-generated API docs.
And the top-level directory can contain README's, Config's and whatnot.
The hard choice is whether or not to use a /src
tree. Python doesn't have a distinction between /src
, /lib
, and /bin
like Java or C has.
Since a top-level /src
directory is seen by some as meaningless, your top-level directory can be the top-level architecture of your application.
/foo
/bar
/baz
I recommend putting all of this under the "name-of-my-product" directory. So, if you're writing an application named quux
, the directory that contains all this stuff is named /quux
.
Another project's PYTHONPATH
, then, can include /path/to/quux/foo
to reuse the QUUX.foo
module.
In my case, since I use Komodo Edit, my IDE cuft is a single .KPF file. I actually put that in the top-level /quux
directory, and omit adding it to SVN.