How to disable pylint 'Undefined variable'

Question

I am hosting IronPython inside a C# application and injecting an API for the host into the global scope.

I have just started to love syntastic for vim with pylint for checking my scripts. But I am getting annoyed by all the [E0602, method_name] Undefined variable 'variable_name' error messages for the injected variables.

I am aware of using # pylint: disable=E0602 to disable this error message, but I'd prefer not to cripple a really useful feature just for some specific variable names.

How do you deal with this?

Currently, I am doing this at the top of my script:

try:
    host_object = getattr(__builtins__, 'host_object')
except AttributeError:
    pass # oops, run this script inside the host application!!

What I would really like to do is this:

# pylint: declare=host_object, other_stuff

Answer 1

Actually, there is a way to disable pylint argues about the specific undefined variable(s) by specifying it in dummy-variables-rgx (or dummy-variables in the older pylint versions). dummy-variables contain _,dummy by default and overwritten with the user-specified values on pylint execution:

$ pylint --dummy-variables-rgx='(_+[a-zA-Z0-9]*?$)|dummy|host_object'

or for the older pylint versions:

$ pylint --dummy-variables='_,dummy,host_object'

Or in case of the pylint configuration for VSCode (User/Workspace Settings can be opened by pressing Ctrl + ,):

"python.linting.pylintArgs": [
    "--dummy-variables-rgx='(_+[a-zA-Z0-9]*?$)|dummy|qdict'"
]

Answer 2

Disabling E0602 in the code:

# make pylint think that it knows about 'injected_var' variable
injected_var = injected_var  # pylint:disable=invalid-name,used-before-assignment

Obviously, that needs to be done once per module, all occurrences of injected_var after this line would be legal for pylint.

Answer 3

Not for variables, but you can disable it for the lines that have the var. See the ref.

Answer 4

I just faced this issue and I just added disable options in pylintrc file. In my case, I am working on a small script and some of pylint checks are a bit overkill. So I disabled Undefined Variable Error

E: 32,40: Undefined variable 'description' (undefined-variable)

by

disable=E0602, E0603

You can find the codes and meaning at: http://pylint-messages.wikidot.com/all-codes

My pylintrc file:

# The format of this file isn't really documented; just use --generate-rcfile
[MASTER]
# Add <file or directory> to the black list. It should be a base name, not a
# path. You may set this option multiple times.
#
# dirname, then we'll need to expand the ignore features in pylint :/
ignore=.git,tools, etc
[MESSAGES CONTROL]
# NOTE(gus): This is a long list.  A number of these are important and
# should be re-enabled once the offending code is fixed (or marked
# with a local disable)
disable=E0602, E0603,
# "F" Fatal errors that prevent further processing
 import-error,
# "I" Informational noise
 locally-disabled,
# "E" Error for important programming issues (likely bugs)
 access-member-before-definition,
 no-member,
 no-method-argument,
 no-self-argument,
# "W" Warnings for stylistic problems or minor programming issues
 abstract-method,
 arguments-differ,
 attribute-defined-outside-init,
 bad-builtin,
 bad-indentation,
 broad-except,
 dangerous-default-value,
 deprecated-lambda,
 deprecated-module,
 duplicate-key,
 expression-not-assigned,
 fixme,
 global-statement,
 no-init,
 non-parent-init-called,
 not-callable,
 protected-access,
 redefined-builtin,
 redefined-outer-name,
 signature-differs,
 star-args,
 super-init-not-called,
 super-on-old-class,
 unpacking-non-sequence,
 unused-argument,
 unused-import,
# "C" Coding convention violations
 invalid-name,
 missing-docstring,
 superfluous-parens,
 bad-continuation,
 Undefined variable,
# "R" Refactor recommendations
 abstract-class-little-used,
 abstract-class-not-used,
 duplicate-code,
 interface-not-implemented,
 no-self-use,
 too-few-public-methods,
 too-many-ancestors,
 too-many-arguments,
 too-many-branches,
 too-many-instance-attributes,
 too-many-lines,
 too-many-locals,
 too-many-public-methods,
 too-many-return-statements,
 too-many-statements


[BASIC]
# Variable names can be 1 to 31 characters long, with lowercase and underscores
variable-rgx=[a-z_][a-z0-9_]{0,30}$

# Argument names can be 2 to 31 characters long, with lowercase and underscores
argument-rgx=[a-z_][a-z0-9_]{1,30}$

# Method names should be at least 3 characters long
# and be lowecased with underscores
method-rgx=([a-z_][a-z0-9_]{2,}|setUp|tearDown)$

# Module names matching vulcan-* are ok (files in bin/)
# module-rgx=(([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+)|(vulcan-[a-z0-9_-]+))$
module-rgx=(([a-z_][a-z0-9_]*)|([A-Z][a-zA-Z0-9]+)|([a-z0-9_-]+))$



# Don't require docstrings on tests.
no-docstring-rgx=((__.*__)|([tT]est.*)|setUp|tearDown)$

[FORMAT]
# Maximum number of characters on a single line.
max-line-length=79

[VARIABLES]
# List of additional names supposed to be defined in builtins. Remember that
# you should avoid to define new builtins when possible.
# _ is used by our localization
additional-builtins=_

[CLASSES]
# List of interface methods to ignore, separated by a comma.
ignore-iface-methods=

[IMPORTS]
# Deprecated modules which should not be used, separated by a comma
deprecated-modules=
# should use openstack.common.jsonutils
 json

[TYPECHECK]
# List of module names for which member attributes should not be checked
ignored-modules=six.moves,_MovedItems

[REPORTS]
# Tells whether to display a full report or only the messages
reports=no

Answer 5

You can add your variables to the 'additional-builtins' option so pylint will consider them as defined.

This has to be done in a rc file, it can't be done inlined in the code.

Answer 6

There's good-names=host_object,other_stuff or additional-builtins=... for this, or for some advanced stuff you can modify the regex via variable-rgx.