nightmare with relative imports, how does pep 366 work?

Question

I have a \"canonical file structure\" like that (I\'m giving sensible names to ease the reading):

mainpack/

  __main__.py
  __init__.py 

  - helpers/
              


        

Answer 1

The loading code seems to be something like this:

    try:
        return sys.modules[pkgname]
    except KeyError:
        if level < 1:
            warn("Parent module '%s' not found while handling "
                 "absolute import" % pkgname, RuntimeWarning, 1)
            return None
        else:
            raise SystemError, ("Parent module '%s' not loaded, cannot "
                                "perform relative import" % pkgname)

which makes me think that maybe your module is not on sys.path. If you start Python (normally) and just type "import mainpack" on the prompt, what does it do? It should be able to find it.

I have tried it myself and got the same error. After reading a bit I found the following solution:

# foo/__main__.py
import sys
mod = __import__('foo')
sys.modules["foo"]=mod

__package__='foo'
from .bar import hello

hello()

It seems a bit hackish to me but it does work. The trick seems to be making sure package foo is loaded so the import can be relative.