The imp module lets you load a module at run-time, knowing just the name of the module.

Playing with imp Module

Make a file "eraseme.py":

   1 print "Successfully imported!"

Then, at the python shell,

   1 >>> import imp
   2 >>> returned = imp.find_module("eraseme", ["."])
   3 >>> returned
   4 (<open file 'eraseme.py', mode 'U' at 0xb7f62220>, 'eraseme.py', ('.py', 'U', 1))
   5 >>>

The find_module line searches for "eraseme" in the current working directory (".").

The first two returned items are self-explanatory, but what about that tuple- ('.py', 'U', 1) ..?

The first (".py") is obviously the extension.

'U' means, "I opened the file in UniversalNewline mode." Basically, universal newline mode is like read ("r"), except that it interprets all newline forms the same way.

Finally, the 1 is a code that matches against imp.PY_SOURCE (1), imp.PY_COMPILED (2), or imp.C_EXTENSION (3). Basically, it's telling us that the .py file is a source file.

Once you have this stuff, it's easy to load:

   1 >>> eraseme = imp.load_module("eraseme", returned[0], returned[1], returned[2])
   2 successfully imported!
   3 >>> eraseme
   4 <module 'eraseme' from './eraseme.py'

Note that, you don't have to play by the rules. If you wanted to, you could have said:

   1 >>> module = imp.load_module("eggs", returned[0], "spam.py", returned[2])
   2 successfully imported!
   3 >>> module
   4 <module 'eggs' from 'spam.py'>
   5 >>> dir(module)
   6 ['__builtins__', '__doc__', '__file__', '__name__']
   7 >>> module.__name__
   8 'eggs'
   9 >>> module.__file__
  10 'spam.py'
  11 >>>

...even though the file's real name is "eggs.py".

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Playing with imp Module

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