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# Copyright (c) 2009 Google, Inc.
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 2 of the License, or (at your option) any later
# version.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
"""checker for use of Python logging
"""
from logilab import astng
from pylint import checkers
from pylint import interfaces
EAGER_STRING_INTERPOLATION = 'W6501'
CHECKED_CONVENIENCE_FUNCTIONS = set([
'critical', 'debug', 'error', 'exception', 'fatal', 'info', 'warn',
'warning'])
class LoggingChecker(checkers.BaseChecker):
"""Checks use of the logging module."""
__implements__ = interfaces.IASTNGChecker
name = 'logging'
msgs = {EAGER_STRING_INTERPOLATION:
('Specify string format arguments as logging function parameters',
'Used when a logging statement has a call form of '
'"logging.<logging method>(format_string % (format_args...))". '
'Such calls should leave string interpolation to the logging '
'method itself and be written '
'"logging.<logging method>(format_string, format_args...)" '
'so that the program may avoid incurring the cost of the '
'interpolation in those cases in which no message will be '
'logged. For more, see '
'http://www.python.org/dev/peps/pep-0282/.')
}
def visit_module(self, unused_node):
"""Clears any state left in this checker from last module checked."""
# The code being checked can just as easily "import logging as foo",
# so it is necessary to process the imports and store in this field
# what name the logging module is actually given.
self._logging_name = None
def visit_import(self, node):
"""Checks to see if this module uses Python's built-in logging."""
for module, as_name in node.names:
if module == 'logging':
if as_name:
self._logging_name = as_name
else:
self._logging_name = 'logging'
def visit_callfunc(self, node):
"""Checks calls to (simple forms of) logging methods."""
if (not isinstance(node.func, astng.Getattr)
or not isinstance(node.func.expr, astng.Name)
or node.func.expr.name != self._logging_name):
return
self._CheckConvenienceMethods(node)
self._CheckLogMethod(node)
def _CheckConvenienceMethods(self, node):
"""Checks calls to logging convenience methods (like logging.warn)."""
if node.func.attrname not in CHECKED_CONVENIENCE_FUNCTIONS:
return
if not node.args:
# Either no args, or star args, or double-star args. Beyond the
# scope of this checker in any case.
return
if isinstance(node.args[0], astng.BinOp) and node.args[0].op == '%':
self.add_message(EAGER_STRING_INTERPOLATION, node=node)
def _CheckLogMethod(self, node):
"""Checks calls to logging.log(level, format, *format_args)."""
if node.func.attrname != 'log':
return
if len(node.args) < 2:
# Either a malformed call or something with crazy star args or
# double-star args magic. Beyond the scope of this checker.
return
if isinstance(node.args[1], astng.BinOp) and node.args[1].op == '%':
self.add_message(EAGER_STRING_INTERPOLATION, node=node)
def register(linter):
"""Required method to auto-register this checker."""
linter.register_checker(LoggingChecker(linter))
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