Cyclic Imports to fix R0401 from pylint

Question

Pylint complains about cyclic import with R0401 error code for a specific file of the NLTK package, e.g.

nltk/nltk/ccg/lexicon.py:1: [R0401(cyclic-import), ] Cyclic import (nltk -> nltk.internals)
nltk/nltk/ccg/lexicon.py:1: [R0401(cyclic-import), ] Cyclic import (nltk.corpus -> nltk.tokenize -> nltk.tokenize.punkt -> nltk.probability)
nltk/nltk/ccg/lexicon.py:1: [R0401(cyclic-import), ] Cyclic import (nltk.corpus -> nltk.tokenize -> nltk.tokenize.texttiling)
nltk/nltk/ccg/lexicon.py:1: [R0401(cyclic-import), ] Cyclic import (nltk.draw.tree -> nltk.tree)
nltk/nltk/ccg/lexicon.py:1: [R0401(cyclic-import), ] Cyclic import (nltk.tree -> nltk.treeprettyprinter)
nltk/nltk/ccg/lexicon.py:1: [R0401(cyclic-import), ] Cyclic import (nltk.grammar -> nltk.parse.pchart)
nltk/nltk/ccg/lexicon.py:1: [R0401(cyclic-import), ] Cyclic import (nltk.stem -> nltk.stem.porter)
nltk/nltk/ccg/lexicon.py:1: [R0401(cyclic-import), ] Cyclic import (nltk.classify.maxent -> nltk.classify.tadm)

The full list is on https://github.com/nltk/nltk/issues/2113

But looking at the imports:

from __future__ import unicode_literals from 

import re
from collections import defaultdict

from nltk.ccg.api import PrimitiveCategory, Direction, CCGVar, FunctionalCategory
from nltk.compat import python_2_unicode_compatible
from nltk.internals import deprecated

from nltk.sem.logic import *

But look at the nltk.internals https://github.com/nltk/nltk/blob/develop/nltk/internals.py , there isn't any cyclic imports that points to nltk.ccg.lexicon:

from __future__ import print_function

import subprocess
import os
import fnmatch
import re
import warnings
import textwrap
import types
import sys
import stat
import locale

# Use the c version of ElementTree, which is faster, if possible:
try:
    from xml.etree import cElementTree as ElementTree
except ImportError:
    from xml.etree import ElementTree

from six import string_types

from nltk import __file__
from nltk import compat

What does the R0401(cyclic-import) message mean?

Looking at the nltk.ccg.lexicon.py and nltk.internals.py There isn't any imports that's cyclic, so how could the problem be resolved.

Isometropia

Answer 1

Not sure why pylint reports these in the nltk/nltk/ccg/lexicon.py file, but the cyclic imports themselves can be seen on the right in the error message.

Taking the first error: Cyclic import (nltk -> nltk.internals): the root __init__.py has an import from nltk.internals, and internals.py has an import from the package root, which is obviously a cyclic import.

Kneecap