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base.py
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base.py
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# 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) 2013-2020 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, 2019 Ashley Whetter <ashley@awhetter.co.uk>
# Copyright (c) 2016, 2018 Jakub Wilk <jwilk@jwilk.net>
# 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 Yannack <yannack@users.noreply.github.com>
# Copyright (c) 2016 Alex Jurkiewicz <alex@jurkiewi.cz>
# Copyright (c) 2017, 2019-2021 Pierre Sassoulas <pierre.sassoulas@gmail.com>
# Copyright (c) 2017, 2019-2021 hippo91 <guillaume.peillex@gmail.com>
# Copyright (c) 2017 danields <danields761@gmail.com>
# Copyright (c) 2017 Jacques Kvam <jwkvam@gmail.com>
# Copyright (c) 2017 ttenhoeve-aa <ttenhoeve@appannie.com>
# Copyright (c) 2018-2019 Nick Drozd <nicholasdrozd@gmail.com>
# Copyright (c) 2018-2019 Ville Skyttä <ville.skytta@iki.fi>
# Copyright (c) 2018 Sergei Lebedev <185856+superbobry@users.noreply.github.com>
# Copyright (c) 2018 Lucas Cimon <lucas.cimon@gmail.com>
# Copyright (c) 2018 ssolanki <sushobhitsolanki@gmail.com>
# Copyright (c) 2018 Natalie Serebryakova <natalie.serebryakova@Natalies-MacBook-Pro.local>
# Copyright (c) 2018 Sushobhit <31987769+sushobhit27@users.noreply.github.com>
# Copyright (c) 2018 SergeyKosarchuk <sergeykosarchuk@gmail.com>
# Copyright (c) 2018 Steven M. Vascellaro <svascellaro@gmail.com>
# Copyright (c) 2018 Mike Frysinger <vapier@gmail.com>
# Copyright (c) 2018 Chris Lamb <chris@chris-lamb.co.uk>
# Copyright (c) 2018 glmdgrielson <32415403+glmdgrielson@users.noreply.github.com>
# Copyright (c) 2019 Daniel Draper <Germandrummer92@users.noreply.github.com>
# Copyright (c) 2019 Hugo van Kemenade <hugovk@users.noreply.github.com>
# Copyright (c) 2019 Niko Wenselowski <niko@nerdno.de>
# Copyright (c) 2019 Nikita Sobolev <mail@sobolevn.me>
# Copyright (c) 2019 Oisín Moran <OisinMoran@users.noreply.github.com>
# Copyright (c) 2019 Fantix King <fantix@uchicago.edu>
# Copyright (c) 2020 Peter Kolbus <peter.kolbus@gmail.com>
# Copyright (c) 2020 ethan-leba <ethanleba5@gmail.com>
# Copyright (c) 2020 へーさん <hira9603859504@gmail.com>
# Copyright (c) 2020 Damien Baty <damien.baty@polyconseil.fr>
# Copyright (c) 2020 Ram Rachum <ram@rachum.com>
# Copyright (c) 2020 Anthony Sottile <asottile@umich.edu>
# Copyright (c) 2020 bernie gray <bfgray3@users.noreply.github.com>
# Copyright (c) 2020 Gabriel R Sezefredo <g@briel.dev>
# Copyright (c) 2020 Benny <benny.mueller91@gmail.com>
# Copyright (c) 2020 Anubhav <35621759+anubh-v@users.noreply.github.com>
# Copyright (c) 2021 Marc Mueller <30130371+cdce8p@users.noreply.github.com>
# Copyright (c) 2021 Lorena B <46202743+lorena-b@users.noreply.github.com>
# Copyright (c) 2021 David Liu <david@cs.toronto.edu>
# Copyright (c) 2021 Andreas Finkler <andi.finkler@gmail.com>
# Copyright (c) 2021 Or Bahari <orbahari@mail.tau.ac.il>
# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
# For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
"""basic checker for Python code"""
import collections
import itertools
import re
import sys
from typing import Pattern
import astroid
from astroid import nodes
from pylint import checkers, exceptions, interfaces
from pylint import utils as lint_utils
from pylint.checkers import utils
from pylint.checkers.utils import (
infer_all,
is_overload_stub,
is_property_deleter,
is_property_setter,
)
from pylint.reporters.ureports import nodes as reporter_nodes
class NamingStyle:
"""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."""
ANY: Pattern[str] = re.compile(".*")
CLASS_NAME_RGX: Pattern[str] = ANY
MOD_NAME_RGX: Pattern[str] = ANY
CONST_NAME_RGX: Pattern[str] = ANY
COMP_VAR_RGX: Pattern[str] = ANY
DEFAULT_NAME_RGX: Pattern[str] = ANY
CLASS_ATTRIBUTE_RGX: Pattern[str] = ANY
@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,
"class_const": cls.CONST_NAME_RGX,
"inlinevar": cls.COMP_VAR_RGX,
}[name_type]
class SnakeCaseStyle(NamingStyle):
"""Regex rules for snake_case naming style."""
CLASS_NAME_RGX = re.compile(r"[^\W\dA-Z][^\WA-Z]+$")
MOD_NAME_RGX = re.compile(r"[^\W\dA-Z][^\WA-Z]*$")
CONST_NAME_RGX = re.compile(r"([^\W\dA-Z][^\WA-Z]*|__.*__)$")
COMP_VAR_RGX = re.compile(r"[^\W\dA-Z][^\WA-Z]*$")
DEFAULT_NAME_RGX = re.compile(
r"([^\W\dA-Z][^\WA-Z]{2,}|_[^\WA-Z]*|__[^\WA-Z\d_][^\WA-Z]+__)$"
)
CLASS_ATTRIBUTE_RGX = re.compile(r"([^\W\dA-Z][^\WA-Z]{2,}|__.*__)$")
class CamelCaseStyle(NamingStyle):
"""Regex rules for camelCase naming style."""
CLASS_NAME_RGX = re.compile(r"[^\W\dA-Z][^\W_]+$")
MOD_NAME_RGX = re.compile(r"[^\W\dA-Z][^\W_]*$")
CONST_NAME_RGX = re.compile(r"([^\W\dA-Z][^\W_]*|__.*__)$")
COMP_VAR_RGX = re.compile(r"[^\W\dA-Z][^\W_]*$")
DEFAULT_NAME_RGX = re.compile(r"([^\W\dA-Z][^\W_]{2,}|__[^\W\dA-Z_]\w+__)$")
CLASS_ATTRIBUTE_RGX = re.compile(r"([^\W\dA-Z][^\W_]{2,}|__.*__)$")
class PascalCaseStyle(NamingStyle):
"""Regex rules for PascalCase naming style."""
CLASS_NAME_RGX = re.compile(r"[^\W\da-z][^\W_]+$")
MOD_NAME_RGX = re.compile(r"[^\W\da-z][^\W_]+$")
CONST_NAME_RGX = re.compile(r"([^\W\da-z][^\W_]*|__.*__)$")
COMP_VAR_RGX = re.compile(r"[^\W\da-z][^\W_]+$")
DEFAULT_NAME_RGX = re.compile(r"([^\W\da-z][^\W_]{2,}|__[^\W\dA-Z_]\w+__)$")
CLASS_ATTRIBUTE_RGX = re.compile(r"[^\W\da-z][^\W_]{2,}$")
class UpperCaseStyle(NamingStyle):
"""Regex rules for UPPER_CASE naming style."""
CLASS_NAME_RGX = re.compile(r"[^\W\da-z][^\Wa-z]+$")
MOD_NAME_RGX = re.compile(r"[^\W\da-z][^\Wa-z]+$")
CONST_NAME_RGX = re.compile(r"([^\W\da-z][^\Wa-z]*|__.*__)$")
COMP_VAR_RGX = re.compile(r"[^\W\da-z][^\Wa-z]+$")
DEFAULT_NAME_RGX = re.compile(r"([^\W\da-z][^\Wa-z]{2,}|__[^\W\dA-Z_]\w+__)$")
CLASS_ATTRIBUTE_RGX = re.compile(r"[^\W\da-z][^\Wa-z]{2,}$")
class AnyStyle(NamingStyle):
pass
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", "==", "!="))
LITERAL_NODE_TYPES = (nodes.Const, nodes.Dict, nodes.List, nodes.Set)
UNITTEST_CASE = "unittest.case"
TYPE_QNAME = "builtins.type"
ABC_METACLASSES = {"_py_abc.ABCMeta", "abc.ABCMeta"} # Python 3.7+,
# Name categories that are always consistent with all naming conventions.
EXEMPT_NAME_CATEGORIES = {"exempt", "ignore"}
# A mapping from 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()", "{}", "[]"],
),
**{
x: f"{x}()"
for x in (
"collections.deque",
"collections.ChainMap",
"collections.Counter",
"collections.OrderedDict",
"collections.defaultdict",
"collections.UserDict",
"collections.UserList",
)
},
)
REVERSED_COMPS = {"<": ">", "<=": ">=", ">": "<", ">=": "<="}
COMPARISON_OPERATORS = frozenset(("==", "!=", "<", ">", "<=", ">="))
# List of methods which can be redefined
REDEFINABLE_METHODS = frozenset(("__module__",))
TYPING_FORWARD_REF_QNAME = "typing.ForwardRef"
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, nodes.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((nodes.ImportFrom, nodes.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,
(
nodes.For,
nodes.ListComp,
nodes.SetComp,
nodes.DictComp,
nodes.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 = (nodes.For, nodes.While)
parent = break_node.parent
while not isinstance(parent, loop_nodes) or break_node in getattr(
parent, "orelse", []
):
break_node = parent
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 = (nodes.For, nodes.While)
definition_nodes = (nodes.FunctionDef, nodes.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(nodes.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)
)
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 = {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: nodes.FunctionDef, config=None):
"""Determine the name type whose regex the a function's name should match.
:param node: A function node.
: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 is_property_setter(node) or is_property_deleter(node):
# If the function is decorated using the prop_method.{setter,getter}
# form, treat it like an attribute as well.
return "attr"
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, nodes.Name) or (
isinstance(decorator, nodes.Attribute)
and decorator.attrname in property_names
):
inferred = utils.safe_infer(decorator)
if (
inferred
and hasattr(inferred, "qname")
and inferred.qname() in property_classes
):
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 as e:
raise exceptions.EmptyReportError() from e
nice_stats[node_type] = {}
if total != 0:
try:
documented = total - stats["undocumented_" + node_type]
percent = (documented * 100.0) / total
nice_stats[node_type]["percent_documented"] = f"{percent:.2f}"
except KeyError:
nice_stats[node_type]["percent_documented"] = "NC"
try:
percent = (stats["badname_" + node_type] * 100.0) / total
nice_stats[node_type]["percent_badname"] = f"{percent:.2f}"
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 = lint_utils.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, nodes.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.",
),
"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.",
),
"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.",
),
"E0115": (
"Name %r is nonlocal and global",
"nonlocal-and-global",
"Emitted when a name is both nonlocal and global.",
),
"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.",
{"maxversion": (3, 8)},
),
"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",
),
"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)
def _too_many_starred_for_tuple(self, assign_tuple):
starred_count = 0
for elem in assign_tuple.itered():
if isinstance(elem, nodes.Tuple):
return self._too_many_starred_for_tuple(elem)
if isinstance(elem, nodes.Starred):
starred_count += 1
return starred_count > 1
@utils.check_messages("too-many-star-expressions", "invalid-star-assignment-target")
def visit_assign(self, node):
# Check *a, *b = ...
assign_target = node.targets[0]
# Check *a = b
if isinstance(node.targets[0], nodes.Starred):
self.add_message("invalid-star-assignment-target", node=node)
if not isinstance(assign_target, nodes.Tuple):
return
if self._too_many_starred_for_tuple(assign_target):
self.add_message("too-many-star-expressions", 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, nodes.Call):
# f(*args) is converted to Call(args=[Starred]), so ignore
# them for this check.
return
if isinstance(node.parent, (nodes.List, nodes.Tuple, nodes.Set, nodes.Dict)):
# PEP 448 unpacking.
return
stmt = node.statement()
if not isinstance(stmt, nodes.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(
nodes.Return, skip_klass=(nodes.FunctionDef, nodes.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)
# Check for duplicate names by clustering args with same name for detailed report
arg_clusters = collections.defaultdict(list)
arguments = filter(None, [node.args.args, node.args.kwonlyargs])
for arg in itertools.chain.from_iterable(arguments):
arg_clusters[arg.name].append(arg)
# provide detailed report about each repeated argument
for argument_duplicates in arg_clusters.values():
if len(argument_duplicates) != 1:
for argument in argument_duplicates:
self.add_message(
"duplicate-argument-name",
line=argument.lineno,
node=argument,
args=(argument.name,),
)
visit_asyncfunctiondef = visit_functiondef
def _check_name_used_prior_global(self, node):
scope_globals = {
name: child
for child in node.nodes_of_class(nodes.Global)
for name in child.names
if child.scope() is node
}
if not scope_globals:
return
for node_name in node.nodes_of_class(nodes.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(nodes.Nonlocal)
if same_scope(child)
)
)
if not nonlocals:
return
global_vars = set(
from_iter(
child.names
for child in node.nodes_of_class(nodes.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(), nodes.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, nodes.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, (nodes.ClassDef, nodes.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, nodes.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.
"""
for inferred in infer_all(node.func):
self._check_inferred_class_is_abstract(inferred, node)
def _check_inferred_class_is_abstract(self, inferred, node):
if not isinstance(inferred, nodes.ClassDef):
return
klass = utils.node_frame_class(node)
if klass is inferred:
# 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
abstract_methods = _has_abstract_methods(inferred)
if not abstract_methods:
return
metaclass = inferred.metaclass()
if metaclass is None:
# Python 3.4 has `abc.ABC`, which won't be detected
# by ClassNode.metaclass()
for ancestor in inferred.ancestors():
if ancestor.qname() == "abc.ABC":
self.add_message(
"abstract-class-instantiated", args=(inferred.name,), node=node
)
break
return
if metaclass.qname() in ABC_METACLASSES:
self.add_message(
"abstract-class-instantiated", args=(inferred.name,), node=node
)
def _check_yield_outside_func(self, node):
if not isinstance(node.frame(), (nodes.FunctionDef, nodes.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, (nodes.For, nodes.While)):
if node not in _node.orelse:
return
if isinstance(_node, (nodes.ClassDef, nodes.FunctionDef)):
break
if (
isinstance(_node, nodes.TryFinally)
and node in _node.finalbody
and isinstance(node, nodes.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"""
parent_frame = node.parent.frame()
# Ignore function stubs created for type information
redefinitions = parent_frame.locals[node.name]
defined_self = next(
(local for local in redefinitions if not utils.is_overload_stub(local)),
node,
)
if defined_self is not node and not astroid.are_exclusive(node, defined_self):
# Additional checks for methods which are not considered
# redefined, since they are already part of the base API.
if (
isinstance(parent_frame, nodes.ClassDef)
and node.name in REDEFINABLE_METHODS
):
return
# Skip typing.overload() functions.
if utils.is_overload_stub(node):
return
# Exempt functions redefined on a condition.
if isinstance(node.parent, nodes.If):
# Exempt "if not <func>" cases
if (
isinstance(node.parent.test, nodes.UnaryOp)
and node.parent.test.op == "not"
and isinstance(node.parent.test.operand, nodes.Name)
and node.parent.test.operand.name == node.name
):
return
# Exempt "if <func> is not None" cases
# pylint: disable=too-many-boolean-expressions
if (
isinstance(node.parent.test, nodes.Compare)
and isinstance(node.parent.test.left, nodes.Name)
and node.parent.test.left.name == node.name
and node.parent.test.ops[0][0] == "is"
and isinstance(node.parent.test.ops[0][1], nodes.Const)
and node.parent.test.ops[0][1].value is None
):
return
# Check if we have forward references for this node.
try:
redefinition_index = redefinitions.index(node)
except ValueError:
pass
else:
for redefinition in redefinitions[:redefinition_index]:
inferred = utils.safe_infer(redefinition)
if (
inferred
and isinstance(inferred, astroid.Instance)
and inferred.qname() == TYPING_FORWARD_REF_QNAME
):
return
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 !",