Create self contained python executables.

Every one knows the special file "__init__.py". There is another special file "__main__.py". If this file exists in a directory, the python interpreter will try to execute it.

Here is an example:

#fred:$ find . 
. 
./hello 
./hello/__main__.py 

In our example the content of the file is a simple loop that prints hello world.

#fred:$ cat ./hello/__main__.py 
# 
for count in range(3): 
  print 'hello (cruel) world' 

Just call python with the directory name and the python interpreter will execute the file __main__.py

#fred:$ python hello 
hello (cruel) world 
hello (cruel) world 
hello (cruel) world 

Now the interesting part...

Python is capable of importing and executing whatever python code is in a zip file. Therefore we can do the following:

#fred:$ (cd hello; zip -r ../hello.zip .) 
  adding: __main__.py (stored 0%) 
 
#fred:$ python hello.zip 
hello (cruel) world 
hello (cruel) world 
hello (cruel) world 

On any Unix like system we can use a shebang (#!) line at the beginning of a file to pass the content of that file to the interpreter specified after the shebang.

#fred:$ echo '#!/usr/bin/env python' > greetings 
#fred:$ cat hello.zip >> greetings 
#fred:$ chmod a+x greetings 

We can now execute that file.

#fred:$ ./greetings 
hello (cruel) world 
hello (cruel) world 
hello (cruel) world 

Mix that with virtualenv and you will have a powerful way to simply distribute and execute your code.