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Unexpected keyword arg in decorator : Python [duplicate]

I'm trying to disable warning C0321 ("more than one statement on a single line" -- I often put if statements with short single-line results on the same line), in Pylint 0.21.1 (if it matters: astng 0.20.1, common 0.50.3, and Python 2.6.6 (r266:84292, Sep 15 2010, 16:22:56)).
I've tried adding disable=C0321 in the Pylint configuration file, but Pylint insists on reporting it anyway. Variations on that line (like disable=0321 or disable=C321) are flagged as errors, so Pylint does recognize the option properly. It's just ignoring it.
Is this a Pylint bug, or am I doing something wrong? Is there a way around this?
I'd really like to get rid of some of this noise.

pylint --generate-rcfile shows it like this:
[MESSAGES CONTROL]
# Enable the message, report, category or checker with the given id(s). You can
# either give multiple identifier separated by comma (,) or put this option
# multiple time.
#enable=
# Disable the message, report, category or checker with the given id(s). You
# can either give multiple identifier separated by comma (,) or put this option
# multiple time (only on the command line, not in the configuration file where
# it should appear only once).
#disable=
So it looks like your ~/.pylintrc should have the disable= line/s in it inside a section [MESSAGES CONTROL].

Starting from Pylint v. 0.25.3, you can use the symbolic names for disabling warnings instead of having to remember all those code numbers. E.g.:
# pylint: disable=locally-disabled, multiple-statements, fixme, line-too-long
This style is more instructive than cryptic error codes, and also more practical since newer versions of Pylint only output the symbolic name, not the error code.
The correspondence between symbolic names and codes can be found here.
A disable comment can be inserted on its own line, applying the disable to everything that comes after in the same block. Alternatively, it can be inserted at the end of the line for which it is meant to apply.
If Pylint outputs "Locally disabling" messages, you can get rid of them by including the disable locally-disabled first as in the example above.

I had this problem using Eclipse and solved it as follows:
In the pylint folder (e.g. C:\Python26\Lib\site-packages\pylint), hold Shift, right-click and choose to open the windows command in that folder. Type:
lint.py --generate-rcfile > standard.rc
This creates the standard.rc configuration file. Open it in Notepad and under [MESSAGES CONTROL], uncomment
disable= and add the message ID's you want to disable, e.g.:
disable=W0511, C0321
Save the file, and in Eclipse → Window → Preferences → PyDev → *pylint, in the arguments box, type:
--rcfile=C:\Python26\Lib\site-packages\pylint\standard.rc
Now it should work...
You can also add a comment at the top of your code that will be interpreted by Pylint:
# pylint: disable=C0321
Pylint message codes.
Adding e.g. --disable-ids=C0321 in the arguments box does not work.
All available Pylint messages are stored in the dictionary _messages, an attribute of an instance of the pylint.utils.MessagesHandlerMixIn class. When running Pylint with the argument --disable-ids=... (at least without a configuration file), this dictionary is initially empty, raising a KeyError exception within Pylint (pylint.utils.MessagesHandlerMixIn.check_message_id().
In Eclipse, you can see this error-message in the Pylint Console (windows* → show view → Console, select Pylint console from the console options besides the console icon.)

To disable a warning locally in a block, add
# pylint: disable=C0321
to that block.

There are several ways to disable warnings & errors from Pylint. Which one to use has to do with how globally or locally you want to apply the disablement -- an important design decision.
Multiple Approaches
In one or more pylintrc files.
This involves more than the ~/.pylintrc file (in your $HOME directory) as described by Chris Morgan. Pylint will search for rc files, with a precedence that values "closer" files more highly:
A pylintrc file in the current working directory; or
If the current working directory is in a Python module (i.e. it contains an __init__.py file), searching up the hierarchy of Python modules until a pylintrc file is found; or
The file named by the environment variable PYLINTRC; or
If you have a home directory that isn’t /root:
~/.pylintrc; or
~/.config/pylintrc; or
/etc/pylintrc
Note that most of these files are named pylintrc -- only the file in ~ has a leading dot.
To your pylintrc file, add lines to disable specific pylint messages. For example:
[MESSAGES CONTROL]
disable=locally-disabled
Further disables from the pylint command line, as described by Aboo and Cairnarvon. This looks like pylint --disable=bad-builtin. Repeat --disable to suppress additional items.
Further disables from individual Python code lines, as described by Imolit. These look like some statement # pylint: disable=broad-except (extra comment on the end of the original source line) and apply only to the current line. My approach is to always put these on the end of other lines of code so they won't be confused with the block style, see below.
Further disables defined for larger blocks of Python code, up to complete source files.
These look like # pragma pylint: disable=bad-whitespace (note the pragma key word).
These apply to every line after the pragma. Putting a block of these at the top of a file makes the suppressions apply to the whole file. Putting the same block lower in the file makes them apply only to lines following the block. My approach is to always put these on a line of their own so they won't be confused with the single-line style, see above.
When a suppression should only apply within a span of code, use # pragma pylint: enable=bad-whitespace (now using enable not disable) to stop suppressing.
Note that disabling for a single line uses the # pylint syntax while disabling for this line onward uses the # pragma pylint syntax. These are easy to confuse especially when copying & pasting.
Putting It All Together
I usually use a mix of these approaches.
I use ~/.pylintrc for absolutely global standards -- very few of these.
I use project-level pylintrc at different levels within Python modules when there are project-specific standards. Especially when you're taking in code from another person or team, you may find they use conventions that you don't prefer, but you don't want to rework the code. Keeping the settings at this level helps not spread those practices to other projects.
I use the block style pragmas at the top of single source files. I like to turn the pragmas off (stop suppressing messages) in the heat of development even for Pylint standards I don't agree with (like "too few public methods" -- I always get that warning on custom Exception classes) -- but it's helpful to see more / maybe all Pylint messages while you're developing. That way you can find the cases you want to address with single-line pragmas (see below), or just add comments for the next developer to explain why that warning is OK in this case.
I leave some of the block-style pragmas enabled even when the code is ready to check in. I try to use few of those, but when it makes sense for the module, it's OK to do as documentation. However I try to leave as few on as possible, preferably none.
I use the single-line-comment style to address especially potent errors. For example, if there's a place where it actually makes sense to do except Exception as exc, I put the # pylint: disable=broad-except on that line instead of a more global approach because this is a strange exception and needs to be called out, basically as a form of documentation.
Like everything else in Python, you can act at different levels of indirection. My advice is to think about what belongs at what level so you don't end up with a too-lenient approach to Pylint.

This is a FAQ:
4.1 Is it possible to locally disable a particular message?
Yes, this feature has been added in Pylint 0.11. This may be done by
adding
# pylint: disable=some-message,another-one at the desired
block level or at the end of the desired line of code.
4.2 Is there a way to disable a message for a particular module only?
Yes, you can disable or enable (globally disabled) messages at the
module level by adding the corresponding option in a comment at the
top of the file:
# pylint: disable=wildcard-import, method-hidden
# pylint: enable=too-many-lines
You can disable messages by:
numerical ID: E1101, E1102, etc.
symbolic message: no-member, undefined-variable, etc.
the name of a group of checks. You can grab those with pylint --list-groups.
category of checks: C, R, W, etc.
all the checks with all.
See the documentation (or run pylint --list-msgs in the terminal) for the full list of Pylint's messages. The documentation also provide a nice example of how to use this feature.

You can also use the following command:
pylint --disable=C0321 test.py
My Pylint version is 0.25.1.

You just have to add one line to disable what you want to disable.
E.g.,
#pylint: disable = line-too-long, too-many-lines, no-name-in-module, import-error, multiple-imports, pointless-string-statement, wrong-import-order
Add this at the very beginning of your module.

In case this helps someone, if you're using Visual Studio Code, it expects the file to be in UTF-8 encoding. To generate the file, I ran pylint --generate-rcfile | out-file -encoding utf8 .pylintrc in PowerShell.

As per Pylint documentation, the easiest is to use this chart:
C convention-related checks
R refactoring-related checks
W various warnings
E errors, for probable bugs in the code
F fatal, if an error occurred which prevented Pylint from doing further processing.
So one can use:
pylint -j 0 --disable=I,E,R,W,C,F YOUR_FILES_LOC

Sorry for diverging a bit from the initial question, about poster's general preference, which would be better addressed by a global configuration file.
But, as in many popular answers, I tend to prefer seeing in my code what could trigger warnings, and eventually inform contributors as well.
My comment to answer from #imolit needs to stay short, here are some details.
For multiple-statements message, it's probably better to disable it at block or module level, like this
# pylint: disable=multiple-statements
My use-case being now attribute-defined-outside-init in a unittest setup(), I opted for a line-scoped message disabling, using the message code to avoid the line-too-long issue.
class ParserTest(unittest.TestCase):
def setUp(self):
self.parser = create_parser() # pylint: disable=W0201
The correspondance can be found locally with a command like
$ pylint --list-msgs | grep 'outside-init'
:attribute-defined-outside-init (W0201): *Attribute %r defined outside __init__*
Of course, you would similarly retrieve the symbolic name from the code.

Python syntax does permit more than one statement on a line, separated by semicolon (;). However, limiting each line to one statement makes it easier for a human to follow a program's logic when reading through it.
So, another way of solving this issue, is to understand why the lint message is there and not put more than one statement on a line.
Yes, you may find it easier to write multiple statements per line, however, Pylint is for every other reader of your code not just you.

My pylint kept ignoring the disable list in my .pylintrc. Finally, I realized that I was executing:
pylint --disable=all --enable=F,E,W
which was overriding the disable list in my .pylintrc.
The correct command to show only Fatal, Errors, Warnings, is:
pylint --disable=C,R

Edit "C:\Users\Your User\AppData\Roaming\Code\User\settings.json"
and add 'python.linting.pylintArgs' with its lines at the end as shown below:
{
"team.showWelcomeMessage": false,
"python.dataScience.sendSelectionToInteractiveWindow": true,
"git.enableSmartCommit": true,
"powershell.codeFormatting.useCorrectCasing": true,
"files.autoSave": "onWindowChange",
"python.linting.pylintArgs": [
"--load-plugins=pylint_django",
"--errors-only"
],
}

pylint "Undefined variable" in module written in C++/SIP

I export several native C++ classes to Python using SIP. I don't use the resulting maplib_sip.pyd module directly, but rather wrap it in a Python packagepymaplib:
# pymaplib/__init__.py
# Make all of maplib_sip available in pymaplib.
from maplib_sip import *
...
def parse_coordinate(coord_str):
...
# LatLon is a class imported from maplib_sip.
return LatLon(lat_float, lon_float)
Pylint doesn't recognize that LatLon comes from maplib_sip:
error pymaplib parse_coordinate 40 15 Undefined variable 'LatLon'
Unfortunately, the same happens for all the classes from maplib_sip, as well as for most of the code from wxPython (Phoenix) that I use. This effectively makes Pylint worthless for me, as the amount of spurious errors dwarfs the real problems.
additional-builtins doesn't work that well for my problem:
# Both of these don't remove the error:
additional-builtins=maplib_sip.LatLon
additional-builtins=pymaplib.LatLon
# This does remove the error in pymaplib:
additional-builtins=LatLon
# But users of pymaplib still give an error:
# Module 'pymaplib' has no 'LatLon' member
How do I deal with this? Can I somehow tell pylint that maplib_sip.LatLon actually exists? Even better, can it somehow figure that out itself via introspection (which works in IPython, for example)?
I'd rather not have to disable the undefined variable checks, since that's one of the huge benefits of pylint for me.
Program versions:
Pylint 1.2.1,
astroid 1.1.1, common 0.61.0,
Python 3.3.3 [32 bit] on Windows7

you may want to try the new --ignored-modules option, though I'm not sure it will work in your case, beside if you stop using import * (which would probably be a good idea as pylint probably already told you ;).
Rather use short import name, eg import maplib_sip as mls, then prefixed name, eg mls.LatLon where desired.
Notice though that the original problem is worth an issue on pylint tracker (https://bitbucket.org/logilab/pylint/issues) so some investigation will be done to grasp why it doesn't get member of your sip exported module.

Disable all Pylint warnings for a file

We are using Pylint within our build system.
We have a Python package within our code base that has throwaway code, and I'd like to disable all warnings for a module temporarily so I can stop bugging the other devs with these superfluous messages. Is there an easy way to pylint: disable all warnings for a module?

From the Pylint FAQ:
With Pylint < 0.25, add
# pylint: disable-all
at the beginning of the module.
Pylint 0.26.1 and up have renamed that directive to
# pylint: skip-file
(but the first version will be kept for backward compatibility).
In order to ease finding which modules are ignored a information-level message I0013 is emitted. With recent versions of Pylint, if you use the old syntax, an additional I0014 message is emitted.

Pylint has five "categories" for messages (of which I'm aware).
These categories were very obvious in the past, but the numbered Pylint messages have now been replaced by names. For example, C0302 is now too-many-lines. But the 'C' tells us that too-many-lines is a Convention message. This is confusing, because Convention messages frequently just show up as a warning, since many systems (such as Syntastic) seem to classify everything as either a warning or an error. However, the Pylint report still breaks things down into these categories, so it's still definitely supported.
Your question specifically refers to Warnings, and all Pylint Warning message names start with 'W'.
It was a bit difficult for me to track this down, but this answer eventually led me to the answer. Pylint still supports disabling entire categories of messages. So, to disable all Warnings, you would do:
disable=W
This can be used at the command-line:
$ pylint --disable=W myfile.py
Or, you can put it in your pylintrc file:
[MESSAGES CONTROL]
disable=W
Note: you may already have the disable option in your rc file, in which case you should append the 'W' to this list.
Or, you can put it inline in your code, where it will work for the scope into which it is placed:
# pylint: disable=W
To disable it for an entire file, it's best to put it at the very top of the file. However, even at the very top of the file, I found I was still getting the trailing-newlines warning message (technically a convention warning, but I'm getting to that).
In my case, I had a library written by someone from long ago. It worked well, so there was really no need to worry about modern Python convention, etc. All I really cared about were the errors that would likely break my code.
My solution was to disable all the Warning, Convention, and Refactoring messages for this one file only by placing the following Pylint command on the first line:
# pylint: disable=W,C,R
Aside from the aforementioned message for trailing newlines, this did exactly what I needed.

Yes, you can specify # pylint: skip-file in the file, but it is bad practice to disable all warnings for a file.
If you want to disable specific warnings only, this can be done by adding a comment such as # pylint: disable=message-name to disable the specified message for the remainder of the file, or at least until # pylint: enable=message-name.
Example:
# pylint: disable=no-member
class C123:
def __init__(self):
self.foo_x = self.bar_x
# pylint: enable=no-member
class C456:
def __init__(self):
self.foo_x = self.bar_x

Another option is to use the --ignore command line option to skip analysis for some files.

My use case is to run pylint *.py to process all files in a directory, except that I want to skip one particular file.
Adding # pylint: skip-file caused Pylint to fail with I: 8, 0: Ignoring entire file (file-ignored). Adding # pylint: disable=file-ignored does not fix that. Presumably, it's a global error rather than a file-specific one.
The solution was to include --disable=file-ignored in the Pylint command options. It took way too long to figure this out; there shouldn't be a file-ignored error when you explicitly ignore a file.

I just did this for pytest tests organised in to classes and it may be useful to someone. These were throwing up lots of errors but I like the class based structure when I'm running in the cli.
I add this below imports on all my test files and it seems to work. Might be nicer to do it once for the test directory if anyone knows the solution for that, but I don't like to ignore for the whole repo if I can avoid it
# Disable pylint errors for tests organised into classes
# pylint: disable=no-self-use too-few-public-methods
# Disable pylint errors for pytest fixtures
# pylint: disable=unused-argument invalid-name
Using it twice didn't break anything, I checked to make sure. Initially I tried brackets for a 2 line disable but that didn't work. I didn't need commas so removed them.
If anyone knows of a decorator that can mark organisational test classes equivalent to #dataclass let me know.

How do I disable a Pylint warning?

I'm trying to disable warning C0321 ("more than one statement on a single line" -- I often put if statements with short single-line results on the same line), in Pylint 0.21.1 (if it matters: astng 0.20.1, common 0.50.3, and Python 2.6.6 (r266:84292, Sep 15 2010, 16:22:56)).
I've tried adding disable=C0321 in the Pylint configuration file, but Pylint insists on reporting it anyway. Variations on that line (like disable=0321 or disable=C321) are flagged as errors, so Pylint does recognize the option properly. It's just ignoring it.
Is this a Pylint bug, or am I doing something wrong? Is there a way around this?
I'd really like to get rid of some of this noise.

pylint --generate-rcfile shows it like this:
[MESSAGES CONTROL]
# Enable the message, report, category or checker with the given id(s). You can
# either give multiple identifier separated by comma (,) or put this option
# multiple time.
#enable=
# Disable the message, report, category or checker with the given id(s). You
# can either give multiple identifier separated by comma (,) or put this option
# multiple time (only on the command line, not in the configuration file where
# it should appear only once).
#disable=
So it looks like your ~/.pylintrc should have the disable= line/s in it inside a section [MESSAGES CONTROL].

Starting from Pylint v. 0.25.3, you can use the symbolic names for disabling warnings instead of having to remember all those code numbers. E.g.:
# pylint: disable=locally-disabled, multiple-statements, fixme, line-too-long
This style is more instructive than cryptic error codes, and also more practical since newer versions of Pylint only output the symbolic name, not the error code.
The correspondence between symbolic names and codes can be found here.
A disable comment can be inserted on its own line, applying the disable to everything that comes after in the same block. Alternatively, it can be inserted at the end of the line for which it is meant to apply.
If Pylint outputs "Locally disabling" messages, you can get rid of them by including the disable locally-disabled first as in the example above.

I had this problem using Eclipse and solved it as follows:
In the pylint folder (e.g. C:\Python26\Lib\site-packages\pylint), hold Shift, right-click and choose to open the windows command in that folder. Type:
lint.py --generate-rcfile > standard.rc
This creates the standard.rc configuration file. Open it in Notepad and under [MESSAGES CONTROL], uncomment
disable= and add the message ID's you want to disable, e.g.:
disable=W0511, C0321
Save the file, and in Eclipse → Window → Preferences → PyDev → *pylint, in the arguments box, type:
--rcfile=C:\Python26\Lib\site-packages\pylint\standard.rc
Now it should work...
You can also add a comment at the top of your code that will be interpreted by Pylint:
# pylint: disable=C0321
Pylint message codes.
Adding e.g. --disable-ids=C0321 in the arguments box does not work.
All available Pylint messages are stored in the dictionary _messages, an attribute of an instance of the pylint.utils.MessagesHandlerMixIn class. When running Pylint with the argument --disable-ids=... (at least without a configuration file), this dictionary is initially empty, raising a KeyError exception within Pylint (pylint.utils.MessagesHandlerMixIn.check_message_id().
In Eclipse, you can see this error-message in the Pylint Console (windows* → show view → Console, select Pylint console from the console options besides the console icon.)

To disable a warning locally in a block, add
# pylint: disable=C0321
to that block.

There are several ways to disable warnings & errors from Pylint. Which one to use has to do with how globally or locally you want to apply the disablement -- an important design decision.
Multiple Approaches
In one or more pylintrc files.
This involves more than the ~/.pylintrc file (in your $HOME directory) as described by Chris Morgan. Pylint will search for rc files, with a precedence that values "closer" files more highly:
A pylintrc file in the current working directory; or
If the current working directory is in a Python module (i.e. it contains an __init__.py file), searching up the hierarchy of Python modules until a pylintrc file is found; or
The file named by the environment variable PYLINTRC; or
If you have a home directory that isn’t /root:
~/.pylintrc; or
~/.config/pylintrc; or
/etc/pylintrc
Note that most of these files are named pylintrc -- only the file in ~ has a leading dot.
To your pylintrc file, add lines to disable specific pylint messages. For example:
[MESSAGES CONTROL]
disable=locally-disabled
Further disables from the pylint command line, as described by Aboo and Cairnarvon. This looks like pylint --disable=bad-builtin. Repeat --disable to suppress additional items.
Further disables from individual Python code lines, as described by Imolit. These look like some statement # pylint: disable=broad-except (extra comment on the end of the original source line) and apply only to the current line. My approach is to always put these on the end of other lines of code so they won't be confused with the block style, see below.
Further disables defined for larger blocks of Python code, up to complete source files.
These look like # pragma pylint: disable=bad-whitespace (note the pragma key word).
These apply to every line after the pragma. Putting a block of these at the top of a file makes the suppressions apply to the whole file. Putting the same block lower in the file makes them apply only to lines following the block. My approach is to always put these on a line of their own so they won't be confused with the single-line style, see above.
When a suppression should only apply within a span of code, use # pragma pylint: enable=bad-whitespace (now using enable not disable) to stop suppressing.
Note that disabling for a single line uses the # pylint syntax while disabling for this line onward uses the # pragma pylint syntax. These are easy to confuse especially when copying & pasting.
Putting It All Together
I usually use a mix of these approaches.
I use ~/.pylintrc for absolutely global standards -- very few of these.
I use project-level pylintrc at different levels within Python modules when there are project-specific standards. Especially when you're taking in code from another person or team, you may find they use conventions that you don't prefer, but you don't want to rework the code. Keeping the settings at this level helps not spread those practices to other projects.
I use the block style pragmas at the top of single source files. I like to turn the pragmas off (stop suppressing messages) in the heat of development even for Pylint standards I don't agree with (like "too few public methods" -- I always get that warning on custom Exception classes) -- but it's helpful to see more / maybe all Pylint messages while you're developing. That way you can find the cases you want to address with single-line pragmas (see below), or just add comments for the next developer to explain why that warning is OK in this case.
I leave some of the block-style pragmas enabled even when the code is ready to check in. I try to use few of those, but when it makes sense for the module, it's OK to do as documentation. However I try to leave as few on as possible, preferably none.
I use the single-line-comment style to address especially potent errors. For example, if there's a place where it actually makes sense to do except Exception as exc, I put the # pylint: disable=broad-except on that line instead of a more global approach because this is a strange exception and needs to be called out, basically as a form of documentation.
Like everything else in Python, you can act at different levels of indirection. My advice is to think about what belongs at what level so you don't end up with a too-lenient approach to Pylint.

This is a FAQ:
4.1 Is it possible to locally disable a particular message?
Yes, this feature has been added in Pylint 0.11. This may be done by
adding
# pylint: disable=some-message,another-one at the desired
block level or at the end of the desired line of code.
4.2 Is there a way to disable a message for a particular module only?
Yes, you can disable or enable (globally disabled) messages at the
module level by adding the corresponding option in a comment at the
top of the file:
# pylint: disable=wildcard-import, method-hidden
# pylint: enable=too-many-lines
You can disable messages by:
numerical ID: E1101, E1102, etc.
symbolic message: no-member, undefined-variable, etc.
the name of a group of checks. You can grab those with pylint --list-groups.
category of checks: C, R, W, etc.
all the checks with all.
See the documentation (or run pylint --list-msgs in the terminal) for the full list of Pylint's messages. The documentation also provide a nice example of how to use this feature.

You can also use the following command:
pylint --disable=C0321 test.py
My Pylint version is 0.25.1.

You just have to add one line to disable what you want to disable.
E.g.,
#pylint: disable = line-too-long, too-many-lines, no-name-in-module, import-error, multiple-imports, pointless-string-statement, wrong-import-order
Add this at the very beginning of your module.

In case this helps someone, if you're using Visual Studio Code, it expects the file to be in UTF-8 encoding. To generate the file, I ran pylint --generate-rcfile | out-file -encoding utf8 .pylintrc in PowerShell.

As per Pylint documentation, the easiest is to use this chart:
C convention-related checks
R refactoring-related checks
W various warnings
E errors, for probable bugs in the code
F fatal, if an error occurred which prevented Pylint from doing further processing.
So one can use:
pylint -j 0 --disable=I,E,R,W,C,F YOUR_FILES_LOC

Sorry for diverging a bit from the initial question, about poster's general preference, which would be better addressed by a global configuration file.
But, as in many popular answers, I tend to prefer seeing in my code what could trigger warnings, and eventually inform contributors as well.
My comment to answer from #imolit needs to stay short, here are some details.
For multiple-statements message, it's probably better to disable it at block or module level, like this
# pylint: disable=multiple-statements
My use-case being now attribute-defined-outside-init in a unittest setup(), I opted for a line-scoped message disabling, using the message code to avoid the line-too-long issue.
class ParserTest(unittest.TestCase):
def setUp(self):
self.parser = create_parser() # pylint: disable=W0201
The correspondance can be found locally with a command like
$ pylint --list-msgs | grep 'outside-init'
:attribute-defined-outside-init (W0201): *Attribute %r defined outside __init__*
Of course, you would similarly retrieve the symbolic name from the code.

Python syntax does permit more than one statement on a line, separated by semicolon (;). However, limiting each line to one statement makes it easier for a human to follow a program's logic when reading through it.
So, another way of solving this issue, is to understand why the lint message is there and not put more than one statement on a line.
Yes, you may find it easier to write multiple statements per line, however, Pylint is for every other reader of your code not just you.

My pylint kept ignoring the disable list in my .pylintrc. Finally, I realized that I was executing:
pylint --disable=all --enable=F,E,W
which was overriding the disable list in my .pylintrc.
The correct command to show only Fatal, Errors, Warnings, is:
pylint --disable=C,R

Edit "C:\Users\Your User\AppData\Roaming\Code\User\settings.json"
and add 'python.linting.pylintArgs' with its lines at the end as shown below:
{
"team.showWelcomeMessage": false,
"python.dataScience.sendSelectionToInteractiveWindow": true,
"git.enableSmartCommit": true,
"powershell.codeFormatting.useCorrectCasing": true,
"files.autoSave": "onWindowChange",
"python.linting.pylintArgs": [
"--load-plugins=pylint_django",
"--errors-only"
],
}

How do I tell PyLint "it's a variable, not a constant" to stop message C0103?

I have a module-level variable in my Python 2.6 program named "_log", which PyLint complains about:
C0103: Invalid name "_log" (should match (([A-Z_][A-Z0-9_]*)|(__.*__))$)
Having read this answer I understand why it's doing this: it thinks the variable is a constant and applies the constant regex. However, I beg to differ: I think it's a variable. How do I tell PyLint that, so it doesn't complain? How does PyLint determine whether it's a variable or a constant - does it just treat all module-level variables as constants?

# pylint: disable-msg=C0103
Put it in the scope where you want these warnings to be ignored. You can also make the above an end-of-line comment, to disable the message only for that line of code.
IIRC it is true that pylint interprets all module-level variables as being 'constants'.
newer versions of pylint will take this line instead
# pylint: disable=C0103

You can also specify a comma separated list of "good-names" that are always allowed in your pylintrc, eg:
[BASIC]
good-names=_log

Seems to me a bit of refactor might help. Pylint in looking at this as a module, so it would be reasonable not to expect to see variables at this level. Conversely it doesn't complain about vars in classes or functions. The following paradigm seems quite common and solves the issue:
def main():
'''Entry point if called as an executable'''
_log = MyLog() # . . .
if __name__ == '__main__':
main()
This has the benefit that if you have some useful classes, I can import them without running your main. The __name__ is that of the module so the "if" fails.

In newer versions of pylint this line is now
# pylint: disable=C0103
the enable message is as simple
# pylint: enable=C0103

As other answers have indicated you can disable a specific PyLint warning (such C0103) as by including the following line:
# pylint: disable=C0103
but this generates the Locally disabling invalid-name warning. Note that this secondary warning could be useful if you want to be reminded of the disabled warning. If you want to disable the warning silently without altering your config file (which would disable the warning globally) you can use:
# pylint: disable=I0011,C0103
Note that PyLint does not issue a warning that you are disabling I0011!

If you disable a message locally in your file then Pylint will report another different warning!
Locally disabling invalid-name (C0103) [I:locally-disabled]
If your intention is for a clean lint run, and surely that should be the target otherwise why are you bothering, then you can disable that message and the corresponding locally-enabled message in your configuration file:
disable=locally-disabled, locally-enabled