# -*- coding: utf-8 -*-
# Copyright (c) 2006-2016 LOGILAB S.A. (Paris, FRANCE) <contact@logilab.fr>
# Copyright (c) 2010 Daniel Harding <dharding@gmail.com>
# Copyright (c) 2012-2014 Google, Inc.
# Copyright (c) 2013-2017 Claudiu Popa <pcmanticore@gmail.com>
# Copyright (c) 2014 Brett Cannon <brett@python.org>
# Copyright (c) 2014 Arun Persaud <arun@nubati.net>
# Copyright (c) 2015 Nick Bastin <nick.bastin@gmail.com>
# Copyright (c) 2015 Michael Kefeder <oss@multiwave.ch>
# Copyright (c) 2015 Dmitry Pribysh <dmand@yandex.ru>
# Copyright (c) 2015 Stephane Wirtel <stephane@wirtel.be>
# Copyright (c) 2015 Cosmin Poieana <cmin@ropython.org>
# Copyright (c) 2015 Florian Bruhin <me@the-compiler.org>
# Copyright (c) 2015 Radu Ciorba <radu@devrandom.ro>
# Copyright (c) 2015 Ionel Cristian Maries <contact@ionelmc.ro>
# Copyright (c) 2016-2017 Łukasz Rogalski <rogalski.91@gmail.com>
# Copyright (c) 2016 Glenn Matthews <glenn@e-dad.net>
# Copyright (c) 2016 Elias Dorneles <eliasdorneles@gmail.com>
# Copyright (c) 2016 Ashley Whetter <ashley@awhetter.co.uk>
# Copyright (c) 2016 Yannack <yannack@users.noreply.github.com>
# Copyright (c) 2016 Jakub Wilk <jwilk@jwilk.net>
# Copyright (c) 2016 Alex Jurkiewicz <alex@jurkiewi.cz>
# Copyright (c) 2017 Jacques Kvam <jwkvam@gmail.com>
# Copyright (c) 2017 ttenhoeve-aa <ttenhoeve@appannie.com>
# Copyright (c) 2017 hippo91 <guillaume.peillex@gmail.com>
# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
# For details: https://github.com/PyCQA/pylint/blob/master/COPYING
"""basic checker for Python code"""
import collections
import itertools
import sys
import re
import six
from six.moves import zip # pylint: disable=redefined-builtin
import astroid
import astroid.bases
import astroid.scoped_nodes
from pylint import checkers
from pylint import exceptions
from pylint import interfaces
from pylint.checkers import utils
from pylint import reporters
from pylint.checkers.utils import get_node_last_lineno
from pylint.reporters.ureports import nodes as reporter_nodes
import pylint.utils as lint_utils
class NamingStyle(object):
# It may seem counterintuitive that single naming style
# has multiple "accepted" forms of regular expressions,
# but we need to special-case stuff like dunder names
# in method names.
CLASS_NAME_RGX = None
MOD_NAME_RGX = None
CONST_NAME_RGX = None
COMP_VAR_RGX = None
DEFAULT_NAME_RGX = None
CLASS_ATTRIBUTE_RGX = None
@classmethod
def get_regex(cls, name_type):
return {
'module': cls.MOD_NAME_RGX,
'const': cls.CONST_NAME_RGX,
'class': cls.CLASS_NAME_RGX,
'function': cls.DEFAULT_NAME_RGX,
'method': cls.DEFAULT_NAME_RGX,
'attr': cls.DEFAULT_NAME_RGX,
'argument': cls.DEFAULT_NAME_RGX,
'variable': cls.DEFAULT_NAME_RGX,
'class_attribute': cls.CLASS_ATTRIBUTE_RGX,
'inlinevar': cls.COMP_VAR_RGX,
}[name_type]
class SnakeCaseStyle(NamingStyle):
CLASS_NAME_RGX = re.compile('[a-z_][a-z0-9_]+$')
MOD_NAME_RGX = re.compile('([a-z_][a-z0-9_]*)$')
CONST_NAME_RGX = re.compile('(([a-z_][a-z0-9_]*)|(__.*__))$')
COMP_VAR_RGX = re.compile('[a-z_][a-z0-9_]*$')
DEFAULT_NAME_RGX = re.compile('(([a-z_][a-z0-9_]{2,30})|(_[a-z0-9_]*)|(__[a-z][a-z0-9_]+__))$')
CLASS_ATTRIBUTE_RGX = re.compile(r'(([a-z_][a-z0-9_]{2,30}|(__.*__)))$')
class CamelCaseStyle(NamingStyle):
CLASS_NAME_RGX = re.compile('[a-z_][a-zA-Z0-9]+$')
MOD_NAME_RGX = re.compile('([a-z_][a-zA-Z0-9]*)$')
CONST_NAME_RGX = re.compile('(([a-z_][A-Za-z0-9]*)|(__.*__))$')
COMP_VAR_RGX = re.compile('[a-z_][A-Za-z0-9]*$')
DEFAULT_NAME_RGX = re.compile('(([a-z_][a-zA-Z0-9]{2,30})|(__[a-z][a-zA-Z0-9_]+__))$')
CLASS_ATTRIBUTE_RGX = re.compile(r'([a-z_][A-Za-z0-9]{2,30}|(__.*__))$')
class PascalCaseStyle(NamingStyle):
CLASS_NAME_RGX = re.compile('[A-Z_][a-zA-Z0-9]+$')
MOD_NAME_RGX = re.compile('[A-Z_][a-zA-Z0-9]+$')
CONST_NAME_RGX = re.compile('(([A-Z_][A-Za-z0-9]*)|(__.*__))$')
COMP_VAR_RGX = re.compile('[A-Z_][a-zA-Z0-9]+$')
DEFAULT_NAME_RGX = re.compile('[A-Z_][a-zA-Z0-9]{2,30}$|(__[a-z][a-zA-Z0-9_]+__)$')
CLASS_ATTRIBUTE_RGX = re.compile('[A-Z_][a-zA-Z0-9]{2,30}$')
class UpperCaseStyle(NamingStyle):
CLASS_NAME_RGX = re.compile('[A-Z_][A-Z0-9_]+$')
MOD_NAME_RGX = re.compile('[A-Z_][A-Z0-9_]+$')
CONST_NAME_RGX = re.compile('(([A-Z_][A-Z0-9_]*)|(__.*__))$')
COMP_VAR_RGX = re.compile('[A-Z_][A-Z0-9_]+$')
DEFAULT_NAME_RGX = re.compile('([A-Z_][A-Z0-9_]{2,30})|(__[a-z][a-zA-Z0-9_]+__)$')
CLASS_ATTRIBUTE_RGX = re.compile('[A-Z_][A-Z0-9_]{2,30}$')
class AnyStyle(NamingStyle):
@classmethod
def get_regex(cls, name_type):
return re.compile('.*')
NAMING_STYLES = {'snake_case': SnakeCaseStyle, 'camelCase': CamelCaseStyle,
'PascalCase': PascalCaseStyle, 'UPPER_CASE': UpperCaseStyle,
'any': AnyStyle}
# do not require a doc string on private/system methods
NO_REQUIRED_DOC_RGX = re.compile('^_')
REVERSED_PROTOCOL_METHOD = '__reversed__'
SEQUENCE_PROTOCOL_METHODS = ('__getitem__', '__len__')
REVERSED_METHODS = (SEQUENCE_PROTOCOL_METHODS,
(REVERSED_PROTOCOL_METHOD, ))
TYPECHECK_COMPARISON_OPERATORS = frozenset(('is', 'is not', '==',
'!=', 'in', 'not in'))
LITERAL_NODE_TYPES = (astroid.Const, astroid.Dict, astroid.List, astroid.Set)
UNITTEST_CASE = 'unittest.case'
BUILTINS = six.moves.builtins.__name__
TYPE_QNAME = "%s.type" % BUILTINS
PY33 = sys.version_info >= (3, 3)
PY3K = sys.version_info >= (3, 0)
PY35 = sys.version_info >= (3, 5)
# Name categories that are always consistent with all naming conventions.
EXEMPT_NAME_CATEGORIES = {'exempt', 'ignore'}
# A mapping from builtin-qname -> symbol, to be used when generating messages
# about dangerous default values as arguments
DEFAULT_ARGUMENT_SYMBOLS = dict(
zip(['.'.join([BUILTINS, x]) for x in ('set', 'dict', 'list')],
['set()', '{}', '[]'])
)
REVERSED_COMPS = {'<': '>', '<=': '>=', '>': '<', '>=': '<='}
def _redefines_import(node):
""" Detect that the given node (AssignName) is inside an
exception handler and redefines an import from the tryexcept body.
Returns True if the node redefines an import, False otherwise.
"""
current = node
while current and not isinstance(current.parent, astroid.ExceptHandler):
current = current.parent
if not current or not utils.error_of_type(current.parent, ImportError):
return False
try_block = current.parent.parent
for import_node in try_block.nodes_of_class((astroid.ImportFrom, astroid.Import)):
for name, alias in import_node.names:
if alias:
if alias == node.name:
return True
elif name == node.name:
return True
return False
def in_loop(node):
"""return True if the node is inside a kind of for loop"""
parent = node.parent
while parent is not None:
if isinstance(parent, (astroid.For, astroid.ListComp, astroid.SetComp,
astroid.DictComp, astroid.GeneratorExp)):
return True
parent = parent.parent
return False
def in_nested_list(nested_list, obj):
"""return true if the object is an element of <nested_list> or of a nested
list
"""
for elmt in nested_list:
if isinstance(elmt, (list, tuple)):
if in_nested_list(elmt, obj):
return True
elif elmt == obj:
return True
return False
def _get_break_loop_node(break_node):
"""
Returns the loop node that holds the break node in arguments.
Args:
break_node (astroid.Break): the break node of interest.
Returns:
astroid.For or astroid.While: the loop node holding the break node.
"""
loop_nodes = (astroid.For, astroid.While)
parent = break_node.parent
while not isinstance(parent, loop_nodes) or break_node in getattr(parent, 'orelse', []):
parent = parent.parent
if parent is None:
break
return parent
def _loop_exits_early(loop):
"""
Returns true if a loop may ends up in a break statement.
Args:
loop (astroid.For, astroid.While): the loop node inspected.
Returns:
bool: True if the loop may ends up in a break statement, False otherwise.
"""
loop_nodes = (astroid.For, astroid.While)
definition_nodes = (astroid.FunctionDef, astroid.ClassDef)
inner_loop_nodes = [
_node for _node in loop.nodes_of_class(loop_nodes,
skip_klass=definition_nodes)
if _node != loop
]
return any(
_node for _node in loop.nodes_of_class(astroid.Break,
skip_klass=definition_nodes)
if _get_break_loop_node(_node) not in inner_loop_nodes
)
def _is_multi_naming_match(match, node_type, confidence):
return (match is not None and
match.lastgroup is not None and
match.lastgroup not in EXEMPT_NAME_CATEGORIES
and (node_type != 'method' or confidence != interfaces.INFERENCE_FAILURE))
if sys.version_info < (3, 0):
BUILTIN_PROPERTY = '__builtin__.property'
else:
BUILTIN_PROPERTY = 'builtins.property'
def _get_properties(config):
"""Returns a tuple of property classes and names.
Property classes are fully qualified, such as 'abc.abstractproperty' and
property names are the actual names, such as 'abstract_property'.
"""
property_classes = set((BUILTIN_PROPERTY,))
property_names = set() # Not returning 'property', it has its own check.
if config is not None:
property_classes.update(config.property_classes)
property_names.update((prop.rsplit('.', 1)[-1]
for prop in config.property_classes))
return property_classes, property_names
def _determine_function_name_type(node, config=None):
"""Determine the name type whose regex the a function's name should match.
:param node: A function node.
:type node: astroid.node_classes.NodeNG
:param config: Configuration from which to pull additional property classes.
:type config: :class:`optparse.Values`
:returns: One of ('function', 'method', 'attr')
:rtype: str
"""
property_classes, property_names = _get_properties(config)
if not node.is_method():
return 'function'
if node.decorators:
decorators = node.decorators.nodes
else:
decorators = []
for decorator in decorators:
# If the function is a property (decorated with @property
# or @abc.abstractproperty), the name type is 'attr'.
if (isinstance(decorator, astroid.Name) or
(isinstance(decorator, astroid.Attribute) and
decorator.attrname in property_names)):
infered = utils.safe_infer(decorator)
if infered and infered.qname() in property_classes:
return 'attr'
# If the function is decorated using the prop_method.{setter,getter}
# form, treat it like an attribute as well.
elif (isinstance(decorator, astroid.Attribute) and
decorator.attrname in ('setter', 'deleter')):
return 'attr'
return 'method'
def _has_abstract_methods(node):
"""
Determine if the given `node` has abstract methods.
The methods should be made abstract by decorating them
with `abc` decorators.
"""
return len(utils.unimplemented_abstract_methods(node)) > 0
def report_by_type_stats(sect, stats, old_stats):
"""make a report of
* percentage of different types documented
* percentage of different types with a bad name
"""
# percentage of different types documented and/or with a bad name
nice_stats = {}
for node_type in ('module', 'class', 'method', 'function'):
try:
total = stats[node_type]
except KeyError:
raise exceptions.EmptyReportError()
nice_stats[node_type] = {}
if total != 0:
try:
documented = total - stats['undocumented_'+node_type]
percent = (documented * 100.) / total
nice_stats[node_type]['percent_documented'] = '%.2f' % percent
except KeyError:
nice_stats[node_type]['percent_documented'] = 'NC'
try:
percent = (stats['badname_'+node_type] * 100.) / total
nice_stats[node_type]['percent_badname'] = '%.2f' % percent
except KeyError:
nice_stats[node_type]['percent_badname'] = 'NC'
lines = ('type', 'number', 'old number', 'difference',
'%documented', '%badname')
for node_type in ('module', 'class', 'method', 'function'):
new = stats[node_type]
old = old_stats.get(node_type, None)
if old is not None:
diff_str = reporters.diff_string(old, new)
else:
old, diff_str = 'NC', 'NC'
lines += (node_type, str(new), str(old), diff_str,
nice_stats[node_type].get('percent_documented', '0'),
nice_stats[node_type].get('percent_badname', '0'))
sect.append(reporter_nodes.Table(children=lines, cols=6, rheaders=1))
def redefined_by_decorator(node):
"""return True if the object is a method redefined via decorator.
For example:
@property
def x(self): return self._x
@x.setter
def x(self, value): self._x = value
"""
if node.decorators:
for decorator in node.decorators.nodes:
if (isinstance(decorator, astroid.Attribute) and
getattr(decorator.expr, 'name', None) == node.name):
return True
return False
class _BasicChecker(checkers.BaseChecker):
__implements__ = interfaces.IAstroidChecker
name = 'basic'
class BasicErrorChecker(_BasicChecker):
msgs = {
'E0100': ('__init__ method is a generator',
'init-is-generator',
'Used when the special class method __init__ is turned into a '
'generator by a yield in its body.'),
'E0101': ('Explicit return in __init__',
'return-in-init',
'Used when the special class method __init__ has an explicit '
'return value.'),
'E0102': ('%s already defined line %s',
'function-redefined',
'Used when a function / class / method is redefined.'),
'E0103': ('%r not properly in loop',
'not-in-loop',
'Used when break or continue keywords are used outside a loop.'),
'E0104': ('Return outside function',
'return-outside-function',
'Used when a "return" statement is found outside a function or '
'method.'),
'E0105': ('Yield outside function',
'yield-outside-function',
'Used when a "yield" statement is found outside a function or '
'method.'),
'E0106': ('Return with argument inside generator',
'return-arg-in-generator',
'Used when a "return" statement with an argument is found '
'outside in a generator function or method (e.g. with some '
'"yield" statements).',
{'maxversion': (3, 3)}),
'E0107': ("Use of the non-existent %s operator",
'nonexistent-operator',
"Used when you attempt to use the C-style pre-increment or"
"pre-decrement operator -- and ++, which doesn't exist in Python."),
'E0108': ('Duplicate argument name %s in function definition',
'duplicate-argument-name',
'Duplicate argument names in function definitions are syntax'
' errors.'),
'E0110': ('Abstract class %r with abstract methods instantiated',
'abstract-class-instantiated',
'Used when an abstract class with `abc.ABCMeta` as metaclass '
'has abstract methods and is instantiated.'),
'W0120': ('Else clause on loop without a break statement',
'useless-else-on-loop',
'Loops should only have an else clause if they can exit early '
'with a break statement, otherwise the statements under else '
'should be on the same scope as the loop itself.'),
'E0112': ('More than one starred expression in assignment',
'too-many-star-expressions',
'Emitted when there are more than one starred '
'expressions (`*x`) in an assignment. This is a SyntaxError.',
{'minversion': (3, 0)}),
'E0113': ('Starred assignment target must be in a list or tuple',
'invalid-star-assignment-target',
'Emitted when a star expression is used as a starred '
'assignment target.',
{'minversion': (3, 0)}),
'E0114': ('Can use starred expression only in assignment target',
'star-needs-assignment-target',
'Emitted when a star expression is not used in an '
'assignment target.',
{'minversion': (3, 0)}),
'E0115': ('Name %r is nonlocal and global',
'nonlocal-and-global',
'Emitted when a name is both nonlocal and global.',
{'minversion': (3, 0)}),
'E0116': ("'continue' not supported inside 'finally' clause",
'continue-in-finally',
'Emitted when the `continue` keyword is found '
'inside a finally clause, which is a SyntaxError.'),
'E0117': ("nonlocal name %s found without binding",
'nonlocal-without-binding',
'Emitted when a nonlocal variable does not have an attached '
'name somewhere in the parent scopes',
{'minversion': (3, 0)}),
'E0118': ("Name %r is used prior to global declaration",
'used-prior-global-declaration',
'Emitted when a name is used prior a global declaration, '
'which results in an error since Python 3.6.',
{'minversion': (3, 6)}),
}
@utils.check_messages('function-redefined')
def visit_classdef(self, node):
self._check_redefinition('class', node)
@utils.check_messages('too-many-star-expressions',
'invalid-star-assignment-target')
def visit_assign(self, node):
starred = list(node.targets[0].nodes_of_class(astroid.Starred))
if len(starred) > 1:
self.add_message('too-many-star-expressions', node=node)
# Check *a = b
if isinstance(node.targets[0], astroid.Starred):
self.add_message('invalid-star-assignment-target', node=node)
@utils.check_messages('star-needs-assignment-target')
def visit_starred(self, node):
"""Check that a Starred expression is used in an assignment target."""
if isinstance(node.parent, astroid.Call):
# f(*args) is converted to Call(args=[Starred]), so ignore
# them for this check.
return
if PY35 and isinstance(node.parent,
(astroid.List, astroid.Tuple,
astroid.Set, astroid.Dict)):
# PEP 448 unpacking.
return
stmt = node.statement()
if not isinstance(stmt, astroid.Assign):
return
if stmt.value is node or stmt.value.parent_of(node):
self.add_message('star-needs-assignment-target', node=node)
@utils.check_messages('init-is-generator', 'return-in-init',
'function-redefined', 'return-arg-in-generator',
'duplicate-argument-name', 'nonlocal-and-global',
'used-prior-global-declaration')
def visit_functiondef(self, node):
self._check_nonlocal_and_global(node)
self._check_name_used_prior_global(node)
if (not redefined_by_decorator(node) and
not utils.is_registered_in_singledispatch_function(node)):
self._check_redefinition(node.is_method() and 'method' or 'function', node)
# checks for max returns, branch, return in __init__
returns = node.nodes_of_class(astroid.Return,
skip_klass=(astroid.FunctionDef,
astroid.ClassDef))
if node.is_method() and node.name == '__init__':
if node.is_generator():
self.add_message('init-is-generator', node=node)
else:
values = [r.value for r in returns]
# Are we returning anything but None from constructors
if any(v for v in values if not utils.is_none(v)):
self.add_message('return-in-init', node=node)
elif node.is_generator():
# make sure we don't mix non-None returns and yields
if not PY33:
for retnode in returns:
if isinstance(retnode.value, astroid.Const) and \
retnode.value.value is not None:
self.add_message('return-arg-in-generator', node=node,
line=retnode.fromlineno)
# Check for duplicate names
args = set()
for name in node.argnames():
if name in args:
self.add_message('duplicate-argument-name', node=node, args=(name,))
else:
args.add(name)
visit_asyncfunctiondef = visit_functiondef
def _check_name_used_prior_global(self, node):
scope_globals = {
name: child
for child in node.nodes_of_class(astroid.Global)
for name in child.names
if child.scope() is node
}
for node_name in node.nodes_of_class(astroid.Name):
if node_name.scope() is not node:
continue
name = node_name.name
corresponding_global = scope_globals.get(name)
if not corresponding_global:
continue
global_lineno = corresponding_global.fromlineno
if global_lineno and global_lineno > node_name.fromlineno:
self.add_message('used-prior-global-declaration',
node=node_name, args=(name, ))
def _check_nonlocal_and_global(self, node):
"""Check that a name is both nonlocal and global."""
def same_scope(current):
return current.scope() is node
from_iter = itertools.chain.from_iterable
nonlocals = set(from_iter(
child.names for child in node.nodes_of_class(astroid.Nonlocal)
if same_scope(child)))
global_vars = set(from_iter(
child.names for child in node.nodes_of_class(astroid.Global)
if same_scope(child)))
for name in nonlocals.intersection(global_vars):
self.add_message('nonlocal-and-global',
args=(name, ), node=node)
@utils.check_messages('return-outside-function')
def visit_return(self, node):
if not isinstance(node.frame(), astroid.FunctionDef):
self.add_message('return-outside-function', node=node)
@utils.check_messages('yield-outside-function')
def visit_yield(self, node):
self._check_yield_outside_func(node)
@utils.check_messages('yield-outside-function')
def visit_yieldfrom(self, node):
self._check_yield_outside_func(node)
@utils.check_messages('not-in-loop', 'continue-in-finally')
def visit_continue(self, node):
self._check_in_loop(node, 'continue')
@utils.check_messages('not-in-loop')
def visit_break(self, node):
self._check_in_loop(node, 'break')
@utils.check_messages('useless-else-on-loop')
def visit_for(self, node):
self._check_else_on_loop(node)
@utils.check_messages('useless-else-on-loop')
def visit_while(self, node):
self._check_else_on_loop(node)
@utils.check_messages('nonexistent-operator')
def visit_unaryop(self, node):
"""check use of the non-existent ++ and -- operator operator"""
if ((node.op in '+-') and
isinstance(node.operand, astroid.UnaryOp) and
(node.operand.op == node.op)):
self.add_message('nonexistent-operator', node=node, args=node.op*2)
def _check_nonlocal_without_binding(self, node, name):
current_scope = node.scope()
while True:
if current_scope.parent is None:
break
if not isinstance(current_scope, (astroid.ClassDef, astroid.FunctionDef)):
self.add_message('nonlocal-without-binding', args=(name, ),
node=node)
return
if name not in current_scope.locals:
current_scope = current_scope.parent.scope()
continue
# Okay, found it.
return
if not isinstance(current_scope, astroid.FunctionDef):
self.add_message('nonlocal-without-binding', args=(name, ), node=node)
@utils.check_messages('nonlocal-without-binding')
def visit_nonlocal(self, node):
for name in node.names:
self._check_nonlocal_without_binding(node, name)
@utils.check_messages('abstract-class-instantiated')
def visit_call(self, node):
""" Check instantiating abstract class with
abc.ABCMeta as metaclass.
"""
try:
for inferred in node.func.infer():
self._check_inferred_class_is_abstract(inferred, node)
except astroid.InferenceError:
return
def _check_inferred_class_is_abstract(self, infered, node):
if not isinstance(infered, astroid.ClassDef):
return
klass = utils.node_frame_class(node)
if klass is infered:
# Don't emit the warning if the class is instantiated
# in its own body or if the call is not an instance
# creation. If the class is instantiated into its own
# body, we're expecting that it knows what it is doing.
return
# __init__ was called
metaclass = infered.metaclass()
abstract_methods = _has_abstract_methods(infered)
if metaclass is None:
# Python 3.4 has `abc.ABC`, which won't be detected
# by ClassNode.metaclass()
for ancestor in infered.ancestors():
if ancestor.qname() == 'abc.ABC' and abstract_methods:
self.add_message('abstract-class-instantiated',
args=(infered.name, ),
node=node)
break
return
if metaclass.qname() == 'abc.ABCMeta' and abstract_methods:
self.add_message('abstract-class-instantiated',
args=(infered.name, ),
node=node)
def _check_yield_outside_func(self, node):
if not isinstance(node.frame(), (astroid.FunctionDef, astroid.Lambda)):
self.add_message('yield-outside-function', node=node)
def _check_else_on_loop(self, node):
"""Check that any loop with an else clause has a break statement."""
if node.orelse and not _loop_exits_early(node):
self.add_message('useless-else-on-loop', node=node,
# This is not optimal, but the line previous
# to the first statement in the else clause
# will usually be the one that contains the else:.
line=node.orelse[0].lineno - 1)
def _check_in_loop(self, node, node_name):
"""check that a node is inside a for or while loop"""
_node = node.parent
while _node:
if isinstance(_node, (astroid.For, astroid.While)):
if node not in _node.orelse:
return
if isinstance(_node, (astroid.ClassDef, astroid.FunctionDef)):
break
if (isinstance(_node, astroid.TryFinally)
and node in _node.finalbody
and isinstance(node, astroid.Continue)):
self.add_message('continue-in-finally', node=node)
_node = _node.parent
self.add_message('not-in-loop', node=node, args=node_name)
def _check_redefinition(self, redeftype, node):
"""check for redefinition of a function / method / class name"""
defined_self = node.parent.frame()[node.name]
if defined_self is not node and not astroid.are_exclusive(node, defined_self):
dummy_variables_rgx = lint_utils.get_global_option(
self, 'dummy-variables-rgx', default=None)
if dummy_variables_rgx and dummy_variables_rgx.match(node.name):
return
self.add_message('function-redefined', node=node,
args=(redeftype, defined_self.fromlineno))
class BasicChecker(_BasicChecker):
"""checks for :
* doc strings
* number of arguments, local variables, branches, returns and statements in
functions, methods
* required module attributes
* dangerous default values as arguments
* redefinition of function / method / class
* uses of the global statement
"""
__implements__ = interfaces.IAstroidChecker
name = 'basic'
msgs = {
'W0101': ('Unreachable code',
'unreachable',
'Used when there is some code behind a "return" or "raise" '
'statement, which will never be accessed.'),
'W0102': ('Dangerous default value %s as argument',
'dangerous-default-value',
'Used when a mutable value as list or dictionary is detected in '
'a default value for an argument.'),
'W0104': ('Statement seems to have no effect',
'pointless-statement',
'Used when a statement doesn\'t have (or at least seems to) '
'any effect.'),
'W0105': ('String statement has no effect',
'pointless-string-statement',
'Used when a string is used as a statement (which of course '
'has no effect). This is a particular case of W0104 with its '
'own message so you can easily disable it if you\'re using '
'those strings as documentation, instead of comments.'),
'W0106': ('Expression "%s" is assigned to nothing',
'expression-not-assigned',
'Used when an expression that is not a function call is assigned '
'to nothing. Probably something else was intended.'),
'W0108': ('Lambda may not be necessary',
'unnecessary-lambda',
'Used when the body of a lambda expression is a function call '
'on the same argument list as the lambda itself; such lambda '
'expressions are in all but a few cases replaceable with the '
'function being called in the body of the lambda.'),
'W0109': ("Duplicate key %r in dictionary",
'duplicate-key',
'Used when a dictionary expression binds the same key multiple '
'times.'),
'W0122': ('Use of exec',
'exec-used',
'Used when you use the "exec" statement (function for Python '
'3), to discourage its usage. That doesn\'t '
'mean you cannot use it !'),
'W0123': ('Use of eval',
'eval-used',
'Used when you use the "eval" function, to discourage its '
'usage. Consider using `ast.literal_eval` for safely evaluating '
'strings containing Python expressions '
'from untrusted sources. '),
'W0150': ("%s statement in finally block may swallow exception",
'lost-exception',
'Used when a break or a return statement is found inside the '
'finally clause of a try...finally block: the exceptions raised '
'in the try clause will be silently swallowed instead of being '
're-raised.'),
'W0199': ('Assert called on a 2-uple. Did you mean \'assert x,y\'?',
'assert-on-tuple',
'A call of assert on a tuple will always evaluate to true if '
'the tuple is not empty, and will always evaluate to false if '
'it is.'),
'W0124': ('Following "as" with another context manager looks like a tuple.',
'confusing-with-statement',
'Emitted when a `with` statement component returns multiple values '
'and uses name binding with `as` only for a part of those values, '
'as in with ctx() as a, b. This can be misleading, since it\'s not '
'clear if the context manager returns a tuple or if the node without '
'a name binding is another context manager.'),
'W0125': ('Using a conditional statement with a constant value',
'using-constant-test',
'Emitted when a conditional statement (If or ternary if) '
'uses a constant value for its test. This might not be what '
'the user intended to do.'),
'E0111': ('The first reversed() argument is not a sequence',
'bad-reversed-sequence',
'Used when the first argument to reversed() builtin '
'isn\'t a sequence (does not implement __reversed__, '
'nor __getitem__ and __len__'),
}
reports = (('RP0101', 'Statistics by type', report_by_type_stats),)
def __init__(self, linter):
_BasicChecker.__init__(self, linter)
self.stats = None
self._tryfinallys = None
def open(self):
"""initialize visit variables and statistics
"""
self._tryfinallys = []
self.stats = self.linter.add_stats(module=0, function=0,
method=0, class_=0)
@utils.check_messages('using-constant-test')
def visit_if(self, node):
self._check_using_constant_test(node, node.test)
@utils.check_messages('using-constant-test')
def visit_ifexp(self, node):
self._check_using_constant_test(node, node.test)
@utils.check_messages('using-constant-test')
def visit_comprehension(self, node):
if node.ifs:
for if_test in node.ifs:
self._check_using_constant_test(node, if_test)
def _check_using_constant_test(self, node, test):
const_nodes = (
astroid.Module,
astroid.scoped_nodes.GeneratorExp,
astroid.Lambda, astroid.FunctionDef, astroid.ClassDef,
astroid.bases.Generator, astroid.UnboundMethod,
astroid.BoundMethod, astroid.Module)
structs = (astroid.Dict, astroid.Tuple, astroid.Set)
# These nodes are excepted, since they are not constant
# values, requiring a computation to happen. The only type
# of node in this list which doesn't have this property is
# Attribute, which is excepted because the conditional statement
# can be used to verify that the attribute was set inside a class,
# which is definitely a valid use case.
except_nodes = (astroid.Attribute, astroid.Call,
astroid.BinOp, astroid.BoolOp, astroid.UnaryOp,
astroid.Subscript)
inferred = None
emit = isinstance(test, (astroid.Const, ) + structs + const_nodes)
if not isinstance(test, except_nodes):
inferred = utils.safe_infer(test)
if emit or isinstance(inferred, const_nodes):
self.add_message('using-constant-test', node=node)
def visit_module(self, _):
"""check module name, docstring and required arguments
"""
self.stats['module'] += 1
def visit_classdef(self, node): # pylint: disable=unused-argument
"""check module name, docstring and redefinition
increment branch counter
"""
self.stats['class'] += 1
@utils.check_messages('pointless-statement', 'pointless-string-statement',
'expression-not-assigned')
def visit_expr(self, node):
"""check for various kind of statements without effect"""
expr = node.value
if isinstance(expr, astroid.Const) and isinstance(expr.value,
six.string_types):
# treat string statement in a separated message
# Handle PEP-257 attribute docstrings.
# An attribute docstring is defined as being a string right after
# an assignment at the module level, class level or __init__ level.
scope = expr.scope()
if isinstance(scope, (astroid.ClassDef, astroid.Module, astroid.FunctionDef)):
if isinstance(scope, astroid.FunctionDef) and scope.name != '__init__':
pass
else:
sibling = expr.previous_sibling()
if (sibling is not None and sibling.scope() is scope and
isinstance(sibling, astroid.Assign)):
return
self.add_message('pointless-string-statement', node=node)
return
# ignore if this is :
# * a direct function call
# * the unique child of a try/except body
# * a yield (which are wrapped by a discard node in _ast XXX)
# warn W0106 if we have any underlying function call (we can't predict
# side effects), else pointless-statement
if (isinstance(expr, (astroid.Yield, astroid.Await, astroid.Call)) or
(isinstance(node.parent, astroid.TryExcept) and
node.parent.body == [node])):
return
if any(expr.nodes_of_class(astroid.Call)):
self.add_message('expression-not-assigned', node=node,
args=expr.as_string())
else:
self.add_message('pointless-statement', node=node)
@staticmethod
def _filter_vararg(node, call_args):
# Return the arguments for the given call which are
# not passed as vararg.
for arg in call_args:
if isinstance(arg, astroid.Starred):
if (isinstance(arg.value, astroid.Name)
and arg.value.name != node.args.vararg):
yield arg
else:
yield arg
@staticmethod
def _has_variadic_argument(args, variadic_name):
if not args:
return True
for arg in args:
if isinstance(arg.value, astroid.Name):
if arg.value.name != variadic_name:
return True
else:
return True
return False
@utils.check_messages('unnecessary-lambda')
def visit_lambda(self, node):
"""check whether or not the lambda is suspicious
"""
# if the body of the lambda is a call expression with the same
# argument list as the lambda itself, then the lambda is
# possibly unnecessary and at least suspicious.
if node.args.defaults:
# If the arguments of the lambda include defaults, then a
# judgment cannot be made because there is no way to check
# that the defaults defined by the lambda are the same as
# the defaults defined by the function called in the body
# of the lambda.
return
call = node.body
if not isinstance(call, astroid.Call):
# The body of the lambda must be a function call expression
# for the lambda to be unnecessary.
return
if (isinstance(node.body.func, astroid.Attribute) and
isinstance(node.body.func.expr, astroid.Call)):
# Chained call, the intermediate call might
# return something else (but we don't check that, yet).
return
ordinary_args = list(node.args.args)
new_call_args = list(self._filter_vararg(node, call.args))
if node.args.kwarg:
if self._has_variadic_argument(call.kwargs, node.args.kwarg):
return
elif call.kwargs or call.keywords:
return
if node.args.vararg:
if self._has_variadic_argument(call.starargs, node.args.vararg):
return
elif call.starargs:
return
# The "ordinary" arguments must be in a correspondence such that:
# ordinary_args[i].name == call.args[i].name.
if len(ordinary_args) != len(new_call_args):
return
for arg, passed_arg in zip(ordinary_args, new_call_args):
if not isinstance(passed_arg, astroid.Name):
return
if arg.name != passed_arg.name:
return
self.add_message('unnecessary-lambda', line=node.fromlineno,
node=node)
@utils.check_messages('dangerous-default-value')
def visit_functiondef(self, node):
"""check function name, docstring, arguments, redefinition,
variable names, max locals
"""
self.stats[node.is_method() and 'method' or 'function'] += 1
self._check_dangerous_default(node)
visit_asyncfunctiondef = visit_functiondef
def _check_dangerous_default(self, node):
# check for dangerous default values as arguments
is_iterable = lambda n: isinstance(n, (astroid.List,
astroid.Set,
astroid.Dict))
for default in node.args.defaults:
try:
value = next(default.infer())
except astroid.InferenceError:
continue
if (isinstance(value, astroid.Instance) and
value.qname() in DEFAULT_ARGUMENT_SYMBOLS):
if value is default:
msg = DEFAULT_ARGUMENT_SYMBOLS[value.qname()]
elif isinstance(value, astroid.Instance) or is_iterable(value):
# We are here in the following situation(s):
# * a dict/set/list/tuple call which wasn't inferred
# to a syntax node ({}, () etc.). This can happen
# when the arguments are invalid or unknown to
# the inference.
# * a variable from somewhere else, which turns out to be a list
# or a dict.
if is_iterable(default):
msg = value.pytype()
elif isinstance(default, astroid.Call):
msg = '%s() (%s)' % (value.name, value.qname())
else:
msg = '%s (%s)' % (default.as_string(), value.qname())
else:
# this argument is a name
msg = '%s (%s)' % (default.as_string(),
DEFAULT_ARGUMENT_SYMBOLS[value.qname()])
self.add_message('dangerous-default-value',
node=node,
args=(msg, ))
@utils.check_messages('unreachable', 'lost-exception')
def visit_return(self, node):
"""1 - check is the node has a right sibling (if so, that's some
unreachable code)
2 - check is the node is inside the finally clause of a try...finally
block
"""
self._check_unreachable(node)
# Is it inside final body of a try...finally bloc ?
self._check_not_in_finally(node, 'return', (astroid.FunctionDef,))
@utils.check_messages('unreachable')
def visit_continue(self, node):
"""check is the node has a right sibling (if so, that's some unreachable
code)
"""
self._check_unreachable(node)
@utils.check_messages('unreachable', 'lost-exception')
def visit_break(self, node):
"""1 - check is the node has a right sibling (if so, that's some
unreachable code)
2 - check is the node is inside the finally clause of a try...finally
block
"""
# 1 - Is it right sibling ?
self._check_unreachable(node)
# 2 - Is it inside final body of a try...finally bloc ?
self._check_not_in_finally(node, 'break', (astroid.For, astroid.While,))
@utils.check_messages('unreachable')
def visit_raise(self, node):
"""check if the node has a right sibling (if so, that's some unreachable
code)
"""
self._check_unreachable(node)
@utils.check_messages('exec-used')
def visit_exec(self, node):
"""just print a warning on exec statements"""
self.add_message('exec-used', node=node)
@utils.check_messages('eval-used', 'exec-used', 'bad-reversed-sequence')
def visit_call(self, node):
"""visit a Call node -> check if this is not a blacklisted builtin
call and check for * or ** use
"""
if isinstance(node.func, astroid.Name):
name = node.func.name
# ignore the name if it's not a builtin (i.e. not defined in the
# locals nor globals scope)
if not (name in node.frame() or
name in node.root()):
if name == 'exec':
self.add_message('exec-used', node=node)
elif name == 'reversed':
self._check_reversed(node)
elif name == 'eval':
self.add_message('eval-used', node=node)
@utils.check_messages('assert-on-tuple')
def visit_assert(self, node):
"""check the use of an assert statement on a tuple."""
if node.fail is None and isinstance(node.test, astroid.Tuple) and \
len(node.test.elts) == 2:
self.add_message('assert-on-tuple', node=node)
@utils.check_messages('duplicate-key')
def visit_dict(self, node):
"""check duplicate key in dictionary"""
keys = set()
for k, _ in node.items:
if isinstance(k, astroid.Const):
key = k.value
if key in keys:
self.add_message('duplicate-key', node=node, args=key)
keys.add(key)
def visit_tryfinally(self, node):
"""update try...finally flag"""
self._tryfinallys.append(node)
def leave_tryfinally(self, node): # pylint: disable=unused-argument
"""update try...finally flag"""
self._tryfinallys.pop()
def _check_unreachable(self, node):
"""check unreachable code"""
unreach_stmt = node.next_sibling()
if unreach_stmt is not None:
self.add_message('unreachable', node=unreach_stmt)
def _check_not_in_finally(self, node, node_name, breaker_classes=()):
"""check that a node is not inside a finally clause of a
try...finally statement.
If we found before a try...finally bloc a parent which its type is
in breaker_classes, we skip the whole check."""
# if self._tryfinallys is empty, we're not a in try...finally bloc
if not self._tryfinallys:
return
# the node could be a grand-grand...-children of the try...finally
_parent = node.parent
_node = node
while _parent and not isinstance(_parent, breaker_classes):
if hasattr(_parent, 'finalbody') and _node in _parent.finalbody:
self.add_message('lost-exception', node=node, args=node_name)
return
_node = _parent
_parent = _node.parent
def _check_reversed(self, node):
""" check that the argument to `reversed` is a sequence """
try:
argument = utils.safe_infer(utils.get_argument_from_call(node, position=0))
except utils.NoSuchArgumentError:
pass
else:
if argument is astroid.YES:
return
if argument is None:
# Nothing was infered.
# Try to see if we have iter().
if isinstance(node.args[0], astroid.Call):
try:
func = next(node.args[0].func.infer())
except astroid.InferenceError:
return
if (getattr(func, 'name', None) == 'iter' and
utils.is_builtin_object(func)):
self.add_message('bad-reversed-sequence', node=node)
return
if isinstance(argument, astroid.Instance):
if (argument._proxied.name == 'dict' and
utils.is_builtin_object(argument._proxied)):
self.add_message('bad-reversed-sequence', node=node)
return
elif any(ancestor.name == 'dict' and utils.is_builtin_object(ancestor)
for ancestor in argument._proxied.ancestors()):
# Mappings aren't accepted by reversed(), unless
# they provide explicitly a __reversed__ method.
try:
argument.locals[REVERSED_PROTOCOL_METHOD]
except KeyError:
self.add_message('bad-reversed-sequence', node=node)
return
for methods in REVERSED_METHODS:
for meth in methods:
try:
argument.getattr(meth)
except astroid.NotFoundError:
break
else:
break
else:
self.add_message('bad-reversed-sequence', node=node)
elif not isinstance(argument, (astroid.List, astroid.Tuple)):
# everything else is not a proper sequence for reversed()
self.add_message('bad-reversed-sequence', node=node)
@utils.check_messages('confusing-with-statement')
def visit_with(self, node):
if not PY3K:
# in Python 2 a "with" statement with multiple managers coresponds
# to multiple nested AST "With" nodes
pairs = []
parent_node = node.parent
if isinstance(parent_node, astroid.With):
# we only care about the direct parent, since this method
# gets called for each with node anyway
pairs.extend(parent_node.items)
pairs.extend(node.items)
else:
# in PY3K a "with" statement with multiple managers coresponds
# to one AST "With" node with multiple items
pairs = node.items
if pairs:
for prev_pair, pair in zip(pairs, pairs[1:]):
if (isinstance(prev_pair[1], astroid.AssignName) and
(pair[1] is None and not isinstance(pair[0], astroid.Call))):
# don't emit a message if the second is a function call
# there's no way that can be mistaken for a name assignment
if PY3K or node.lineno == node.parent.lineno:
# if the line number doesn't match
# we assume it's a nested "with"
self.add_message('confusing-with-statement', node=node)
KNOWN_NAME_TYPES = {
"module", "const", "class", "function", "method", "attr",
"argument", "variable", "class_attribute", "inlinevar"
}
HUMAN_READABLE_TYPES = {
'module': 'module',
'const': 'constant',
'class': 'class',
'function': 'function',
'method': 'method',
'attr': 'attribute',
'argument': 'argument',
'variable': 'variable',
'class_attribute': 'class attribute',
'inlinevar': 'inline iteration',
}
DEFAULT_NAMING_STYLES = {
"module": "snake_case",
"const": "UPPER_CASE",
"class": "PascalCase",
"function": "snake_case",
"method": "snake_case",
"attr": "snake_case",
"argument": "snake_case",
"variable": "snake_case",
"class_attribute": "any",
"inlinevar": "any",
}
def _create_naming_options():
name_options = []
for name_type in KNOWN_NAME_TYPES:
human_readable_name = HUMAN_READABLE_TYPES[name_type]
default_style = DEFAULT_NAMING_STYLES[name_type]
name_type = name_type.replace('_', '-')
name_options.append((
'%s-naming-style' % (name_type,),
{'default': default_style,
'type': 'choice', 'choices': list(NAMING_STYLES.keys()), 'metavar': '<style>',
'help': 'Naming style matching correct %s names' % (human_readable_name,)}),)
name_options.append((
'%s-rgx' % (name_type,),
{'default': None, 'type': 'regexp', 'metavar': '<regexp>',
'help': 'Regular expression matching correct %s names. Overrides %s-naming-style'
% (human_readable_name, name_type,)}))
return tuple(name_options)
class NameChecker(_BasicChecker):
msgs = {
'C0102': ('Black listed name "%s"',
'blacklisted-name',
'Used when the name is listed in the black list (unauthorized '
'names).'),
'C0103': ('%s name "%s" doesn\'t conform to %s',
'invalid-name',
'Used when the name doesn\'t conform to naming rules '
'associated to its type (constant, variable, class...).'),
'W0111': ('Name %s will become a keyword in Python %s',
'assign-to-new-keyword',
'Used when assignment will become invalid in future '
'Python release due to introducing new keyword'),
}
options = (('good-names',
{'default' : ('i', 'j', 'k', 'ex', 'Run', '_'),
'type' :'csv', 'metavar' : '<names>',
'help' : 'Good variable names which should always be accepted,'
' separated by a comma'}
),
('bad-names',
{'default' : ('foo', 'bar', 'baz', 'toto', 'tutu', 'tata'),
'type' :'csv', 'metavar' : '<names>',
'help' : 'Bad variable names which should always be refused, '
'separated by a comma'}
),
('name-group',
{'default' : (),
'type' :'csv', 'metavar' : '<name1:name2>',
'help' : ('Colon-delimited sets of names that determine each'
' other\'s naming style when the name regexes'
' allow several styles.')}
),
('include-naming-hint',
{'default': False, 'type': 'yn', 'metavar': '<y_or_n>',
'help': 'Include a hint for the correct naming format with invalid-name'}
),
('property-classes',
{'default': ('abc.abstractproperty',),
'type': 'csv',
'metavar': '<decorator names>',
'help': 'List of decorators that produce properties, such as '
'abc.abstractproperty. Add to this list to register '
'other decorators that produce valid properties.'}
),
) + _create_naming_options()
KEYWORD_ONSET = {
(3, 0): {'True', 'False'},
(3, 7): {'async', 'await'}
}
def __init__(self, linter):
_BasicChecker.__init__(self, linter)
self._name_category = {}
self._name_group = {}
self._bad_names = {}
self._name_regexps = {}
self._name_hints = {}
def open(self):
self.stats = self.linter.add_stats(badname_module=0,
badname_class=0, badname_function=0,
badname_method=0, badname_attr=0,
badname_const=0,
badname_variable=0,
badname_inlinevar=0,
badname_argument=0,
badname_class_attribute=0)
for group in self.config.name_group:
for name_type in group.split(':'):
self._name_group[name_type] = 'group_%s' % (group,)
regexps, hints = self._create_naming_rules()
self._name_regexps = regexps
self._name_hints = hints
def _create_naming_rules(self):
regexps = {}
hints = {}
for name_type in KNOWN_NAME_TYPES:
naming_style_option_name = "%s_naming_style" % (name_type,)
naming_style_name = getattr(self.config, naming_style_option_name)
regexps[name_type] = NAMING_STYLES[naming_style_name].get_regex(name_type)
custom_regex_setting_name = "%s_rgx" % (name_type, )
custom_regex = getattr(self.config, custom_regex_setting_name, None)
if custom_regex is not None:
regexps[name_type] = custom_regex
if custom_regex is not None:
hints[name_type] = "%r pattern" % custom_regex.pattern
else:
hints[name_type] = "%s naming style" % naming_style_name
return regexps, hints
@utils.check_messages('blacklisted-name', 'invalid-name')
def visit_module(self, node):
self._check_name('module', node.name.split('.')[-1], node)
self._bad_names = {}
def leave_module(self, node): # pylint: disable=unused-argument
for all_groups in six.itervalues(self._bad_names):
if len(all_groups) < 2:
continue
groups = collections.defaultdict(list)
min_warnings = sys.maxsize
for group in six.itervalues(all_groups):
groups[len(group)].append(group)
min_warnings = min(len(group), min_warnings)
if len(groups[min_warnings]) > 1:
by_line = sorted(groups[min_warnings],
key=lambda group: min(warning[0].lineno for warning in group))
warnings = itertools.chain(*by_line[1:])
else:
warnings = groups[min_warnings][0]
for args in warnings:
self._raise_name_warning(*args)
@utils.check_messages('blacklisted-name', 'invalid-name', 'assign-to-new-keyword')
def visit_classdef(self, node):
self._check_assign_to_new_keyword_violation(node.name, node)
self._check_name('class', node.name, node)
for attr, anodes in six.iteritems(node.instance_attrs):
if not any(node.instance_attr_ancestors(attr)):
self._check_name('attr', attr, anodes[0])
@utils.check_messages('blacklisted-name', 'invalid-name', 'assign-to-new-keyword')
def visit_functiondef(self, node):
# Do not emit any warnings if the method is just an implementation
# of a base class method.
self._check_assign_to_new_keyword_violation(node.name, node)
confidence = interfaces.HIGH
if node.is_method():
if utils.overrides_a_method(node.parent.frame(), node.name):
return
confidence = (interfaces.INFERENCE if utils.has_known_bases(node.parent.frame())
else interfaces.INFERENCE_FAILURE)
self._check_name(_determine_function_name_type(node,
config=self.config),
node.name, node, confidence)
# Check argument names
args = node.args.args
if args is not None:
self._recursive_check_names(args, node)
visit_asyncfunctiondef = visit_functiondef
@utils.check_messages('blacklisted-name', 'invalid-name')
def visit_global(self, node):
for name in node.names:
self._check_name('const', name, node)
@utils.check_messages('blacklisted-name', 'invalid-name', 'assign-to-new-keyword')
def visit_assignname(self, node):
"""check module level assigned names"""
self._check_assign_to_new_keyword_violation(node.name, node)
frame = node.frame()
ass_type = node.assign_type()
if isinstance(ass_type, astroid.Comprehension):
self._check_name('inlinevar', node.name, node)
elif isinstance(frame, astroid.Module):
if isinstance(ass_type, astroid.Assign) and not in_loop(ass_type):
if isinstance(utils.safe_infer(ass_type.value), astroid.ClassDef):
self._check_name('class', node.name, node)
else:
if not _redefines_import(node):
# Don't emit if the name redefines an import
# in an ImportError except handler.
self._check_name('const', node.name, node)
elif isinstance(ass_type, astroid.ExceptHandler):
self._check_name('variable', node.name, node)
elif isinstance(frame, astroid.FunctionDef):
# global introduced variable aren't in the function locals
if node.name in frame and node.name not in frame.argnames():
if not _redefines_import(node):
self._check_name('variable', node.name, node)
elif isinstance(frame, astroid.ClassDef):
if not list(frame.local_attr_ancestors(node.name)):
self._check_name('class_attribute', node.name, node)
def _recursive_check_names(self, args, node):
"""check names in a possibly recursive list <arg>"""
for arg in args:
if isinstance(arg, astroid.AssignName):
self._check_name('argument', arg.name, node)
else:
self._recursive_check_names(arg.elts, node)
def _find_name_group(self, node_type):
return self._name_group.get(node_type, node_type)
def _raise_name_warning(self, node, node_type, name, confidence):
type_label = HUMAN_READABLE_TYPES[node_type]
hint = self._name_hints[node_type]
if self.config.include_naming_hint:
hint += " (%r pattern)" % self._name_regexps[node_type].pattern
args = (
type_label.capitalize(),
name,
hint
)
self.add_message('invalid-name', node=node, args=args,
confidence=confidence)
self.stats['badname_' + node_type] += 1
def _check_name(self, node_type, name, node, confidence=interfaces.HIGH):
"""check for a name using the type's regexp"""
if utils.is_inside_except(node):
clobbering, _ = utils.clobber_in_except(node)
if clobbering:
return
if name in self.config.good_names:
return
if name in self.config.bad_names:
self.stats['badname_' + node_type] += 1
self.add_message('blacklisted-name', node=node, args=name)
return
regexp = self._name_regexps[node_type]
match = regexp.match(name)
if _is_multi_naming_match(match, node_type, confidence):
name_group = self._find_name_group(node_type)
bad_name_group = self._bad_names.setdefault(name_group, {})
warnings = bad_name_group.setdefault(match.lastgroup, [])
warnings.append((node, node_type, name, confidence))
if match is None:
self._raise_name_warning(node, node_type, name, confidence)
def _check_assign_to_new_keyword_violation(self, name, node):
keyword_first_version = self._name_became_keyword_in_version(
name, self.KEYWORD_ONSET
)
if keyword_first_version is not None:
self.add_message('assign-to-new-keyword',
node=node, args=(name, keyword_first_version),
confidence=interfaces.HIGH)
@staticmethod
def _name_became_keyword_in_version(name, rules):
for version, keywords in rules.items():
if name in keywords and sys.version_info < version:
return '.'.join(map(str, version))
return None
class DocStringChecker(_BasicChecker):
msgs = {
'C0111': ('Missing %s docstring', # W0131
'missing-docstring',
'Used when a module, function, class or method has no docstring.'
'Some special methods like __init__ doesn\'t necessary require a '
'docstring.'),
'C0112': ('Empty %s docstring', # W0132
'empty-docstring',
'Used when a module, function, class or method has an empty '
'docstring (it would be too easy ;).'),
}
options = (('no-docstring-rgx',
{'default' : NO_REQUIRED_DOC_RGX,
'type' : 'regexp', 'metavar' : '<regexp>',
'help' : 'Regular expression which should only match '
'function or class names that do not require a '
'docstring.'}
),
('docstring-min-length',
{'default' : -1,
'type' : 'int', 'metavar' : '<int>',
'help': ('Minimum line length for functions/classes that'
' require docstrings, shorter ones are exempt.')}
),
)
def open(self):
self.stats = self.linter.add_stats(undocumented_module=0,
undocumented_function=0,
undocumented_method=0,
undocumented_class=0)
@utils.check_messages('missing-docstring', 'empty-docstring')
def visit_module(self, node):
self._check_docstring('module', node)
@utils.check_messages('missing-docstring', 'empty-docstring')
def visit_classdef(self, node):
if self.config.no_docstring_rgx.match(node.name) is None:
self._check_docstring('class', node)
@staticmethod
def _is_setter_or_deleter(node):
names = {'setter', 'deleter'}
for decorator in node.decorators.nodes:
if (isinstance(decorator, astroid.Attribute)
and decorator.attrname in names):
return True
return False
@utils.check_messages('missing-docstring', 'empty-docstring')
def visit_functiondef(self, node):
if self.config.no_docstring_rgx.match(node.name) is None:
ftype = 'method' if node.is_method() else 'function'
if node.decorators and self._is_setter_or_deleter(node):
return
if isinstance(node.parent.frame(), astroid.ClassDef):
overridden = False
confidence = (interfaces.INFERENCE if utils.has_known_bases(node.parent.frame())
else interfaces.INFERENCE_FAILURE)
# check if node is from a method overridden by its ancestor
for ancestor in node.parent.frame().ancestors():
if node.name in ancestor and \
isinstance(ancestor[node.name], astroid.FunctionDef):
overridden = True
break
self._check_docstring(ftype, node,
report_missing=not overridden,
confidence=confidence)
else:
self._check_docstring(ftype, node)
visit_asyncfunctiondef = visit_functiondef
def _check_docstring(self, node_type, node, report_missing=True,
confidence=interfaces.HIGH):
"""check the node has a non empty docstring"""
docstring = node.doc
if docstring is None:
if not report_missing:
return
lines = get_node_last_lineno(node) - node.lineno
if node_type == 'module' and not lines:
# If the module has no body, there's no reason
# to require a docstring.
return
max_lines = self.config.docstring_min_length
if node_type != 'module' and max_lines > -1 and lines < max_lines:
return
self.stats['undocumented_'+node_type] += 1
if (node.body and isinstance(node.body[0], astroid.Expr) and
isinstance(node.body[0].value, astroid.Call)):
# Most likely a string with a format call. Let's see.
func = utils.safe_infer(node.body[0].value.func)
if (isinstance(func, astroid.BoundMethod)
and isinstance(func.bound, astroid.Instance)):
# Strings in Python 3, others in Python 2.
if PY3K and func.bound.name == 'str':
return
elif func.bound.name in ('str', 'unicode', 'bytes'):
return
self.add_message('missing-docstring', node=node, args=(node_type,),
confidence=confidence)
elif not docstring.strip():
self.stats['undocumented_'+node_type] += 1
self.add_message('empty-docstring', node=node, args=(node_type,),
confidence=confidence)
class PassChecker(_BasicChecker):
"""check if the pass statement is really necessary"""
msgs = {'W0107': ('Unnecessary pass statement',
'unnecessary-pass',
'Used when a "pass" statement that can be avoided is '
'encountered.'),
}
@utils.check_messages('unnecessary-pass')
def visit_pass(self, node):
if len(node.parent.child_sequence(node)) > 1:
self.add_message('unnecessary-pass', node=node)
class LambdaForComprehensionChecker(_BasicChecker):
"""check for using a lambda where a comprehension would do.
See <http://www.artima.com/weblogs/viewpost.jsp?thread=98196>
where GvR says comprehensions would be clearer.
"""
msgs = {'W0110': ('map/filter on lambda could be replaced by comprehension',
'deprecated-lambda',
'Used when a lambda is the first argument to "map" or '
'"filter". It could be clearer as a list '
'comprehension or generator expression.',
{'maxversion': (3, 0)}),
}
@utils.check_messages('deprecated-lambda')
def visit_call(self, node):
"""visit a Call node, check if map or filter are called with a
lambda
"""
if not node.args:
return
if not isinstance(node.args[0], astroid.Lambda):
return
infered = utils.safe_infer(node.func)
if (utils.is_builtin_object(infered)
and infered.name in ['map', 'filter']):
self.add_message('deprecated-lambda', node=node)
def _is_one_arg_pos_call(call):
"""Is this a call with exactly 1 argument,
where that argument is positional?
"""
return (isinstance(call, astroid.Call)
and len(call.args) == 1 and not call.keywords)
class ComparisonChecker(_BasicChecker):
"""Checks for comparisons
- singleton comparison: 'expr == True', 'expr == False' and 'expr == None'
- yoda condition: 'const "comp" right' where comp can be '==', '!=', '<',
'<=', '>' or '>=', and right can be a variable, an attribute, a method or
a function
"""
msgs = {'C0121': ('Comparison to %s should be %s',
'singleton-comparison',
'Used when an expression is compared to singleton '
'values like True, False or None.'),
'C0122': ('Comparison should be %s',
'misplaced-comparison-constant',
'Used when the constant is placed on the left side '
'of a comparison. It is usually clearer in intent to '
'place it in the right hand side of the comparison.'),
'C0123': ('Using type() instead of isinstance() for a typecheck.',
'unidiomatic-typecheck',
'The idiomatic way to perform an explicit typecheck in '
'Python is to use isinstance(x, Y) rather than '
'type(x) == Y, type(x) is Y. Though there are unusual '
'situations where these give different results.',
{'old_names': [('W0154', 'unidiomatic-typecheck')]}),
'R0123': ('Comparison to literal',
'literal-comparison',
'Used when comparing an object to a literal, which is usually '
'what you do not want to do, since you can compare to a different '
'literal than what was expected altogether.'),
}
def _check_singleton_comparison(self, singleton, root_node):
if singleton.value is True:
suggestion = "just 'expr' or 'expr is True'"
self.add_message('singleton-comparison',
node=root_node,
args=(True, suggestion))
elif singleton.value is False:
suggestion = "'not expr' or 'expr is False'"
self.add_message('singleton-comparison',
node=root_node,
args=(False, suggestion))
elif singleton.value is None:
self.add_message('singleton-comparison',
node=root_node,
args=(None, "'expr is None'"))
def _check_literal_comparison(self, literal, node):
"""Check if we compare to a literal, which is usually what we do not want to do."""
nodes = (astroid.List,
astroid.Tuple,
astroid.Dict,
astroid.Set)
is_other_literal = isinstance(literal, nodes)
is_const = False
if isinstance(literal, astroid.Const):
if literal.value in (True, False, None):
# Not interested in this values.
return
is_const = isinstance(literal.value, (bytes, str, int, float))
if is_const or is_other_literal:
self.add_message('literal-comparison', node=node)
def _check_misplaced_constant(self, node, left, right, operator):
if isinstance(right, astroid.Const):
return
operator = REVERSED_COMPS.get(operator, operator)
suggestion = '%s %s %r' % (right.as_string(), operator, left.value)
self.add_message('misplaced-comparison-constant', node=node,
args=(suggestion,))
@utils.check_messages('singleton-comparison', 'misplaced-comparison-constant',
'unidiomatic-typecheck', 'literal-comparison')
def visit_compare(self, node):
self._check_unidiomatic_typecheck(node)
# NOTE: this checker only works with binary comparisons like 'x == 42'
# but not 'x == y == 42'
if len(node.ops) != 1:
return
left = node.left
operator, right = node.ops[0]
if (operator in ('<', '<=', '>', '>=', '!=', '==')
and isinstance(left, astroid.Const)):
self._check_misplaced_constant(node, left, right, operator)
if operator == '==':
if isinstance(left, astroid.Const):
self._check_singleton_comparison(left, node)
elif isinstance(right, astroid.Const):
self._check_singleton_comparison(right, node)
if operator in ('is', 'is not'):
self._check_literal_comparison(right, node)
def _check_unidiomatic_typecheck(self, node):
operator, right = node.ops[0]
if operator in TYPECHECK_COMPARISON_OPERATORS:
left = node.left
if _is_one_arg_pos_call(left):
self._check_type_x_is_y(node, left, operator, right)
def _check_type_x_is_y(self, node, left, operator, right):
"""Check for expressions like type(x) == Y."""
left_func = utils.safe_infer(left.func)
if not (isinstance(left_func, astroid.ClassDef)
and left_func.qname() == TYPE_QNAME):
return
if operator in ('is', 'is not') and _is_one_arg_pos_call(right):
right_func = utils.safe_infer(right.func)
if (isinstance(right_func, astroid.ClassDef)
and right_func.qname() == TYPE_QNAME):
# type(x) == type(a)
right_arg = utils.safe_infer(right.args[0])
if not isinstance(right_arg, LITERAL_NODE_TYPES):
# not e.g. type(x) == type([])
return
self.add_message('unidiomatic-typecheck', node=node)
def register(linter):
"""required method to auto register this checker"""
linter.register_checker(BasicErrorChecker(linter))
linter.register_checker(BasicChecker(linter))
linter.register_checker(NameChecker(linter))
linter.register_checker(DocStringChecker(linter))
linter.register_checker(PassChecker(linter))
linter.register_checker(LambdaForComprehensionChecker(linter))
linter.register_checker(ComparisonChecker(linter))
