Pythonic way to resolve circular import statements?

Question

I just inherited some code which makes me uneasy: There is a testing library, full of classes corresponding to webpages on our site, and each webpage class has methods to a

Answer 1

Please read Sebastian's answer for detailed explanation. This approach was proposed by David Beazley in PyCon

Try positioning the imports on the top like this

try:
    from homePageLib import HomePage
except ImportError:
    import sys
    HomePage = sys.modules[__package__ + '.HomePage']

This will try to import your HomePage and if failed, will try to load it from the cache

Answer 2

Resolving these constructs usually involves techniques like Dependency Injection.

It is, however, rather simple to fix this error:

In calendarLib.py:

import homePageLib

class CalendarPage(object):
    def clickHomePageLink(self):
        [...]
        return homePageLib.HomePage()

The code at module level is executed at import time. Using the from [...] import [...] syntax requires the module to be completely initialized to succeed.

A simple import [...] does not, because no symbols are accessed, thus breaking the dependency chain.