message-control.rst

Messages control

pylint has an advanced message control for its checks, offering the ability to enable / disable a message either from the command line or from the configuration file, as well as from the code itself.

For all of these controls, pylint accepts the following values:

• a symbolic message: no-member, undefined-variable etc.
• a numerical ID: E1101, E1102 etc.
• The name of the group of checks. You can grab those with pylint --list-groups. For example, you can disable / enable all the checks related to type checking, with typecheck or all the checks related to variables with variables
• Corresponding category of the checks
  • 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.
• All the checks with all

Block disables

This describes how the pragma controls operate at a code level.

The pragma controls can disable / enable:

• All the violations on a single line

  python

  a, b = ... # pylint: disable=unbalanced-tuple-unpacking

• All the violations in a single scope

  python

  def test():

  # Disable all the no-member violations in this function # pylint: disable=no-member ...

• All the violations in a block. For instance, each separate branch of an if statement is considered a separate block, as in the following example:

  python

  def meth5(self):

  # pylint: disable=no-member # no error print(self.bla) if self.blop: # pylint: enable=no-member # enable all no-members for this block print(self.blip) else: # This is affected by the scope disable print(self.blip) # pylint: enable=no-member print(self.blip) if self.blop: # pylint: disable=no-member # disable all no-members for this block print(self.blip) else: # This emits a violation print(self.blip)

• If the violation occurs on a block starting line, then it applies only to that line

  python

  if self.blop: # pylint: disable=no-member; applies only to this line

  # Here we get an error print(self.blip)

  else:

  # error print(self.blip)

Here's an example with all these rules in a single place:

python

"""pylint option block-disable"""

__revision__ = None

class Foo(object):

"""block-disable test"""

def __init__(self):

pass

def meth1(self, arg):

"""this issues a message""" print(self)

def meth2(self, arg):

"""and this one not""" # pylint: disable=unused-argument print(self + "foo")

def meth3(self):

"""test one line disabling""" # no error print(self.bla) # pylint: disable=no-member # error print(self.blop)

def meth4(self):

"""test re-enabling""" # pylint: disable=no-member # no error print(self.bla) print(self.blop) # pylint: enable=no-member # error print(self.blip)

def meth5(self):

"""test IF sub-block re-enabling""" # pylint: disable=no-member # no error print(self.bla) if self.blop: # pylint: enable=no-member # error print(self.blip) else: # no error print(self.blip) # no error print(self.blip)

def meth6(self):

"""test TRY/EXCEPT sub-block re-enabling""" # pylint: disable=no-member # no error print(self.bla) try: # pylint: enable=no-member # error print(self.blip) except UndefinedName: # pylint: disable=undefined-variable # no error print(self.blip) # no error print(self.blip)

def meth7(self):

"""test one line block opening disabling""" if self.blop: # pylint: disable=no-member # error print(self.blip) else: # error print(self.blip) # error print(self.blip)

def meth8(self):

"""test late disabling""" # error print(self.blip) # pylint: disable=no-member # no error print(self.bla) print(self.blop)

Detecting useless disables

When pylint get better and false positives are removed, disable that became useless can accumulate and clutter the code. In order to clean them you can enable the useless-suppression warning.