Add constants naming rules

[sobolevn]

pep8 implies that constants are named in UPPER_CASE: https://www.python.org/dev/peps/pep-0008/#constants

Right now this code is considered valid:

# Module-level variable:
delta = 10

However, it is not valid. This one is:

# Module-level variable:
DELTA = 10

pylint has checks for it: C: 8, 0: Constant name "delta" doesn't conform to UPPER_CASE naming style (invalid-name)

[5j9]

I'm curious to know how pylint detects constants. Note that if a constant literal (10) is assigned to a variable (delta), that's not enough evidence to call that variable a constant. Some other value can be assigned to the same variable later in the code...

I'd say doable, but requires a more in depth introspection.

[sobolevn]

@5j9 I would say that constant is a misleading name.

'Module level variable' is better. And by convention we name these variables as UPPER_CASE.

[5j9]

Ah, in that case we do not agree on what is considered a constant.
I've always thought of them having a constant value, i.e. I never use UPPER_CASE for a for-loop variable, even if it is defined at the module level. Same for any global variable that gets reassigned or mutated during the execution of the code in that module.

[master468]

I'm looking at the differences between pylint and pep8-naming (through flake8) and came across this page. Has there been any development on this in the past year?

[noorul]

Any update on this? Is anyone using any other plugin other than pylint for this?

[sobolevn]

I use wemake-python-styleguide that has this rule: https://wemake-python-stylegui.de/en/latest/pages/usage/violations/naming.html#global-module-level-variables

[noorul]

I tried adding this, but it takes too much time to complete the scan.

[ipadla]

I made a small plugin for flake8 https://pypi.org/project/flake8-class-constants/
It's dirty, without tests, but it seems to work on small projects