how to handle long path name for pep8 compliance?

Question

How would I handle long path name like below for pep8 compliance? Is 79 characters per line a must even if it becomes somewhat unreadable?

def setUp(self):
    self.patcher1 = patch('projectname.common.credential.CredentialCache.mymethodname')                 

Answer 1

There are multiple ways to do this:

1. Use a variable to store this

   def setUp(self):
       path = 'projectname.common.credential.CredentialCache.mymethodname'
       self.patcher1 = patch(path)
   

2. String concatenation:

   An assignment like v = ("a" "b" "c") gets converted into v = "abc":

   def setUp(self):
       self.patcher1 = patch(
           "projectname.common.credential."
           "CredentialCache.mymethodname")
   

3. Tell pep8 that we don't use 80-column terminals anymore with --max-line-length=100 (or some sufficiently reasonable value). (Hat Tip @chepner below :) )

Answer 2

The 79-character limit in PEP8 is based more on historical beliefs than in actual readability. All of PEP8 is a guideline, but this one is more frequently ignored than most of the recommendation. The pep8 tool even has a specific option for changing the value of what is considered "too long".

pep8 --max-line-length 100 myscript.py

I frequently just disable the test altogether:

pep8 --ignore E501 myscript.py

Answer 3

I prefer variant with concatenation.

def setUp(self):
    self.patcher1 = patch(
        "projectname.common.credential."
        "CredentialCache.mymethodname")

Also concatenation braces are not required when calling a function.