335 lines
13 KiB
Python
335 lines
13 KiB
Python
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# Copyright (c) 2006, 2009-2010, 2012-2015 LOGILAB S.A. (Paris, FRANCE) <contact@logilab.fr>
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# Copyright (c) 2014-2016 Claudiu Popa <pcmanticore@gmail.com>
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# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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# For details: https://github.com/PyCQA/pylint/blob/master/COPYING
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"""check for signs of poor design"""
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from collections import defaultdict
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from astroid import If, BoolOp
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from astroid import decorators
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from pylint.interfaces import IAstroidChecker
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from pylint.checkers import BaseChecker
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from pylint.checkers.utils import check_messages
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from pylint import utils
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MSGS = {
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'R0901': ('Too many ancestors (%s/%s)',
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'too-many-ancestors',
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'Used when class has too many parent classes, try to reduce \
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this to get a simpler (and so easier to use) class.'),
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'R0902': ('Too many instance attributes (%s/%s)',
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'too-many-instance-attributes',
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'Used when class has too many instance attributes, try to reduce \
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this to get a simpler (and so easier to use) class.'),
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'R0903': ('Too few public methods (%s/%s)',
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'too-few-public-methods',
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'Used when class has too few public methods, so be sure it\'s \
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really worth it.'),
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'R0904': ('Too many public methods (%s/%s)',
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'too-many-public-methods',
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'Used when class has too many public methods, try to reduce \
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this to get a simpler (and so easier to use) class.'),
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'R0911': ('Too many return statements (%s/%s)',
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'too-many-return-statements',
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'Used when a function or method has too many return statement, \
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making it hard to follow.'),
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'R0912': ('Too many branches (%s/%s)',
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'too-many-branches',
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'Used when a function or method has too many branches, \
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making it hard to follow.'),
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'R0913': ('Too many arguments (%s/%s)',
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'too-many-arguments',
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'Used when a function or method takes too many arguments.'),
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'R0914': ('Too many local variables (%s/%s)',
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'too-many-locals',
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'Used when a function or method has too many local variables.'),
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'R0915': ('Too many statements (%s/%s)',
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'too-many-statements',
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'Used when a function or method has too many statements. You \
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should then split it in smaller functions / methods.'),
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'R0916': ('Too many boolean expressions in if statement (%s/%s)',
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'too-many-boolean-expressions',
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'Used when a if statement contains too many boolean '
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'expressions'),
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}
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def _count_boolean_expressions(bool_op):
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"""Counts the number of boolean expressions in BoolOp `bool_op` (recursive)
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example: a and (b or c or (d and e)) ==> 5 boolean expressions
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"""
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nb_bool_expr = 0
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for bool_expr in bool_op.get_children():
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if isinstance(bool_expr, BoolOp):
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nb_bool_expr += _count_boolean_expressions(bool_expr)
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else:
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nb_bool_expr += 1
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return nb_bool_expr
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class MisdesignChecker(BaseChecker):
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"""checks for sign of poor/misdesign:
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* number of methods, attributes, local variables...
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* size, complexity of functions, methods
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"""
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__implements__ = (IAstroidChecker,)
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# configuration section name
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name = 'design'
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# messages
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msgs = MSGS
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priority = -2
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# configuration options
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options = (('max-args',
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{'default' : 5, 'type' : 'int', 'metavar' : '<int>',
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'help': 'Maximum number of arguments for function / method'}
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),
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('max-locals',
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{'default' : 15, 'type' : 'int', 'metavar' : '<int>',
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'help': 'Maximum number of locals for function / method body'}
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),
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('max-returns',
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{'default' : 6, 'type' : 'int', 'metavar' : '<int>',
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'help': 'Maximum number of return / yield for function / '
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'method body'}
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),
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('max-branches',
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{'default' : 12, 'type' : 'int', 'metavar' : '<int>',
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'help': 'Maximum number of branch for function / method body'}
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),
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('max-statements',
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{'default' : 50, 'type' : 'int', 'metavar' : '<int>',
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'help': 'Maximum number of statements in function / method '
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'body'}
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),
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('max-parents',
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{'default' : 7,
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'type' : 'int',
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'metavar' : '<num>',
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'help' : 'Maximum number of parents for a class (see R0901).'}
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),
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('max-attributes',
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{'default' : 7,
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'type' : 'int',
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'metavar' : '<num>',
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'help' : 'Maximum number of attributes for a class \
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(see R0902).'}
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),
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('min-public-methods',
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{'default' : 2,
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'type' : 'int',
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'metavar' : '<num>',
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'help' : 'Minimum number of public methods for a class \
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(see R0903).'}
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),
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('max-public-methods',
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{'default' : 20,
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'type' : 'int',
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'metavar' : '<num>',
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'help' : 'Maximum number of public methods for a class \
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(see R0904).'}
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),
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('max-bool-expr',
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{'default': 5,
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'type': 'int',
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'metavar': '<num>',
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'help': 'Maximum number of boolean expressions in a if '
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'statement'}
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),
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)
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def __init__(self, linter=None):
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BaseChecker.__init__(self, linter)
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self.stats = None
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self._returns = None
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self._branches = None
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self._stmts = 0
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def open(self):
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"""initialize visit variables"""
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self.stats = self.linter.add_stats()
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self._returns = []
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self._branches = defaultdict(int)
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@decorators.cachedproperty
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def _ignored_argument_names(self):
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return utils.get_global_option(self, 'ignored-argument-names', default=None)
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@check_messages('too-many-ancestors', 'too-many-instance-attributes',
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'too-few-public-methods', 'too-many-public-methods')
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def visit_classdef(self, node):
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"""check size of inheritance hierarchy and number of instance attributes
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"""
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nb_parents = len(list(node.ancestors()))
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if nb_parents > self.config.max_parents:
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self.add_message('too-many-ancestors', node=node,
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args=(nb_parents, self.config.max_parents))
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if len(node.instance_attrs) > self.config.max_attributes:
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self.add_message('too-many-instance-attributes', node=node,
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args=(len(node.instance_attrs),
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self.config.max_attributes))
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@check_messages('too-few-public-methods', 'too-many-public-methods')
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def leave_classdef(self, node):
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"""check number of public methods"""
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my_methods = sum(1 for method in node.mymethods()
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if not method.name.startswith('_'))
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all_methods = sum(1 for method in node.methods()
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if not method.name.startswith('_'))
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# Does the class contain less than n public methods ?
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# This checks only the methods defined in the current class,
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# since the user might not have control over the classes
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# from the ancestors. It avoids some false positives
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# for classes such as unittest.TestCase, which provides
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# a lot of assert methods. It doesn't make sense to warn
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# when the user subclasses TestCase to add his own tests.
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if my_methods > self.config.max_public_methods:
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self.add_message('too-many-public-methods', node=node,
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args=(my_methods,
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self.config.max_public_methods))
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# stop here for exception, metaclass and interface classes
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if node.type != 'class':
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return
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# Does the class contain more than n public methods ?
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# This checks all the methods defined by ancestors and
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# by the current class.
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if all_methods < self.config.min_public_methods:
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self.add_message('too-few-public-methods', node=node,
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args=(all_methods,
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self.config.min_public_methods))
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@check_messages('too-many-return-statements', 'too-many-branches',
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'too-many-arguments', 'too-many-locals',
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'too-many-statements')
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def visit_functiondef(self, node):
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"""check function name, docstring, arguments, redefinition,
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variable names, max locals
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"""
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# init branch and returns counters
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self._returns.append(0)
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# check number of arguments
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args = node.args.args
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ignored_argument_names = self._ignored_argument_names
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if args is not None:
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ignored_args_num = 0
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if ignored_argument_names:
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ignored_args_num = sum(1 for arg in args if ignored_argument_names.match(arg.name))
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argnum = len(args) - ignored_args_num
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if argnum > self.config.max_args:
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self.add_message('too-many-arguments', node=node,
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args=(len(args), self.config.max_args))
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else:
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ignored_args_num = 0
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# check number of local variables
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locnum = len(node.locals) - ignored_args_num
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if locnum > self.config.max_locals:
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self.add_message('too-many-locals', node=node,
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args=(locnum, self.config.max_locals))
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# init statements counter
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self._stmts = 1
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visit_asyncfunctiondef = visit_functiondef
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@check_messages('too-many-return-statements', 'too-many-branches',
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'too-many-arguments', 'too-many-locals',
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'too-many-statements')
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def leave_functiondef(self, node):
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"""most of the work is done here on close:
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checks for max returns, branch, return in __init__
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"""
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returns = self._returns.pop()
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if returns > self.config.max_returns:
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self.add_message('too-many-return-statements', node=node,
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args=(returns, self.config.max_returns))
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branches = self._branches[node]
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if branches > self.config.max_branches:
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self.add_message('too-many-branches', node=node,
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args=(branches, self.config.max_branches))
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# check number of statements
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if self._stmts > self.config.max_statements:
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self.add_message('too-many-statements', node=node,
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args=(self._stmts, self.config.max_statements))
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leave_asyncfunctiondef = leave_functiondef
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def visit_return(self, _):
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"""count number of returns"""
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if not self._returns:
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return # return outside function, reported by the base checker
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self._returns[-1] += 1
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def visit_default(self, node):
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"""default visit method -> increments the statements counter if
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necessary
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"""
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if node.is_statement:
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self._stmts += 1
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def visit_tryexcept(self, node):
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"""increments the branches counter"""
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branches = len(node.handlers)
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if node.orelse:
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branches += 1
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self._inc_branch(node, branches)
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self._stmts += branches
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def visit_tryfinally(self, node):
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"""increments the branches counter"""
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self._inc_branch(node, 2)
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self._stmts += 2
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@check_messages('too-many-boolean-expressions')
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def visit_if(self, node):
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"""increments the branches counter and checks boolean expressions"""
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self._check_boolean_expressions(node)
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branches = 1
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# don't double count If nodes coming from some 'elif'
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if node.orelse and (len(node.orelse) > 1 or
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not isinstance(node.orelse[0], If)):
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branches += 1
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self._inc_branch(node, branches)
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self._stmts += branches
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def _check_boolean_expressions(self, node):
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"""Go through "if" node `node` and counts its boolean expressions
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if the "if" node test is a BoolOp node
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"""
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condition = node.test
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if not isinstance(condition, BoolOp):
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return
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nb_bool_expr = _count_boolean_expressions(condition)
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if nb_bool_expr > self.config.max_bool_expr:
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self.add_message('too-many-boolean-expressions', node=condition,
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args=(nb_bool_expr, self.config.max_bool_expr))
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def visit_while(self, node):
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"""increments the branches counter"""
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branches = 1
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if node.orelse:
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branches += 1
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self._inc_branch(node, branches)
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visit_for = visit_while
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def _inc_branch(self, node, branchesnum=1):
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"""increments the branches counter"""
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self._branches[node.scope()] += branchesnum
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def register(linter):
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"""required method to auto register this checker """
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linter.register_checker(MisdesignChecker(linter))
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