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-# -*- coding: utf-8 -*-
-# Copyright (c) 2006-2016 LOGILAB S.A. (Paris, FRANCE) <contact@logilab.fr>
-# Copyright (c) 2010 Maarten ter Huurne <maarten@treewalker.org>
-# Copyright (c) 2012-2014 Google, Inc.
-# Copyright (c) 2012 FELD Boris <lothiraldan@gmail.com>
-# Copyright (c) 2013-2018 Claudiu Popa <pcmanticore@gmail.com>
-# Copyright (c) 2014 Michal Nowikowski <godfryd@gmail.com>
-# Copyright (c) 2014 Brett Cannon <brett@python.org>
-# Copyright (c) 2014 Arun Persaud <arun@nubati.net>
-# Copyright (c) 2014 David Pursehouse <david.pursehouse@gmail.com>
-# Copyright (c) 2015 Dmitry Pribysh <dmand@yandex.ru>
-# Copyright (c) 2015 Ionel Cristian Maries <contact@ionelmc.ro>
-# Copyright (c) 2016-2017 Łukasz Rogalski <rogalski.91@gmail.com>
-# Copyright (c) 2016 Alexander Todorov <atodorov@otb.bg>
-# Copyright (c) 2016 Anthony Foglia <afoglia@users.noreply.github.com>
-# Copyright (c) 2016 Florian Bruhin <me@the-compiler.org>
-# Copyright (c) 2016 Moises Lopez <moylop260@vauxoo.com>
-# Copyright (c) 2016 Jakub Wilk <jwilk@jwilk.net>
-# Copyright (c) 2017 hippo91 <guillaume.peillex@gmail.com>
-# Copyright (c) 2018 ssolanki <sushobhitsolanki@gmail.com>
-# Copyright (c) 2018 Ashley Whetter <ashley@awhetter.co.uk>
-# Copyright (c) 2018 Anthony Sottile <asottile@umich.edu>
-# Copyright (c) 2018 Ben Green <benhgreen@icloud.com>
-# Copyright (c) 2018 Ville Skyttä <ville.skytta@upcloud.com>
-# Copyright (c) 2018 Nick Drozd <nicholasdrozd@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
-
-"""classes checker for Python code
-"""
-import collections
-from itertools import chain, zip_longest
-
-import astroid
-from astroid import decorators, objects
-from astroid.bases import BUILTINS, Generator
-from astroid.exceptions import DuplicateBasesError, InconsistentMroError
-from astroid.scoped_nodes import function_to_method
-
-from pylint.checkers import BaseChecker
-from pylint.checkers.utils import (
- PYMETHODS,
- SPECIAL_METHODS_PARAMS,
- check_messages,
- class_is_abstract,
- decorated_with,
- decorated_with_property,
- has_known_bases,
- is_attr_private,
- is_attr_protected,
- is_builtin_object,
- is_comprehension,
- is_iterable,
- is_property_setter,
- is_property_setter_or_deleter,
- is_protocol_class,
- node_frame_class,
- overrides_a_method,
- safe_infer,
- unimplemented_abstract_methods,
-)
-from pylint.interfaces import IAstroidChecker
-from pylint.utils import get_global_option
-
-NEXT_METHOD = "__next__"
-INVALID_BASE_CLASSES = {"bool", "range", "slice", "memoryview"}
-BUILTIN_DECORATORS = {"builtins.property", "builtins.classmethod"}
-
-# Dealing with useless override detection, with regard
-# to parameters vs arguments
-
-_CallSignature = collections.namedtuple(
- "_CallSignature", "args kws starred_args starred_kws"
-)
-_ParameterSignature = collections.namedtuple(
- "_ParameterSignature", "args kwonlyargs varargs kwargs"
-)
-
-
-def _signature_from_call(call):
- kws = {}
- args = []
- starred_kws = []
- starred_args = []
- for keyword in call.keywords or []:
- arg, value = keyword.arg, keyword.value
- if arg is None and isinstance(value, astroid.Name):
- # Starred node and we are interested only in names,
- # otherwise some transformation might occur for the parameter.
- starred_kws.append(value.name)
- elif isinstance(value, astroid.Name):
- kws[arg] = value.name
- else:
- kws[arg] = None
-
- for arg in call.args:
- if isinstance(arg, astroid.Starred) and isinstance(arg.value, astroid.Name):
- # Positional variadic and a name, otherwise some transformation
- # might have occurred.
- starred_args.append(arg.value.name)
- elif isinstance(arg, astroid.Name):
- args.append(arg.name)
- else:
- args.append(None)
-
- return _CallSignature(args, kws, starred_args, starred_kws)
-
-
-def _signature_from_arguments(arguments):
- kwarg = arguments.kwarg
- vararg = arguments.vararg
- args = [arg.name for arg in arguments.args if arg.name != "self"]
- kwonlyargs = [arg.name for arg in arguments.kwonlyargs]
- return _ParameterSignature(args, kwonlyargs, vararg, kwarg)
-
-
-def _definition_equivalent_to_call(definition, call):
- """Check if a definition signature is equivalent to a call."""
- if definition.kwargs:
- same_kw_variadics = definition.kwargs in call.starred_kws
- else:
- same_kw_variadics = not call.starred_kws
- if definition.varargs:
- same_args_variadics = definition.varargs in call.starred_args
- else:
- same_args_variadics = not call.starred_args
- same_kwonlyargs = all(kw in call.kws for kw in definition.kwonlyargs)
- same_args = definition.args == call.args
-
- no_additional_kwarg_arguments = True
- if call.kws:
- for keyword in call.kws:
- is_arg = keyword in call.args
- is_kwonly = keyword in definition.kwonlyargs
- if not is_arg and not is_kwonly:
- # Maybe this argument goes into **kwargs,
- # or it is an extraneous argument.
- # In any case, the signature is different than
- # the call site, which stops our search.
- no_additional_kwarg_arguments = False
- break
-
- return all(
- (
- same_args,
- same_kwonlyargs,
- same_args_variadics,
- same_kw_variadics,
- no_additional_kwarg_arguments,
- )
- )
-
-
-# Deal with parameters overridding in two methods.
-
-
-def _positional_parameters(method):
- positional = method.args.args
- if method.type in ("classmethod", "method"):
- positional = positional[1:]
- return positional
-
-
-def _get_node_type(node, potential_types):
- """
- Return the type of the node if it exists in potential_types.
-
- Args:
- node (astroid.node): node to get the type of.
- potential_types (tuple): potential types of the node.
-
- Returns:
- type: type of the node or None.
- """
- for potential_type in potential_types:
- if isinstance(node, potential_type):
- return potential_type
- return None
-
-
-def _check_arg_equality(node_a, node_b, attr_name):
- """
- Check equality of nodes based on the comparison of their attributes named attr_name.
-
- Args:
- node_a (astroid.node): first node to compare.
- node_b (astroid.node): second node to compare.
- attr_name (str): name of the nodes attribute to use for comparison.
-
- Returns:
- bool: True if node_a.attr_name == node_b.attr_name, False otherwise.
- """
- return getattr(node_a, attr_name) == getattr(node_b, attr_name)
-
-
-def _has_different_parameters_default_value(original, overridden):
- """
- Check if original and overridden methods arguments have different default values
-
- Return True if one of the overridden arguments has a default
- value different from the default value of the original argument
- If one of the method doesn't have argument (.args is None)
- return False
- """
- if original.args is None or overridden.args is None:
- return False
-
- all_args = chain(original.args, original.kwonlyargs)
- original_param_names = [param.name for param in all_args]
- default_missing = object()
- for param_name in original_param_names:
- try:
- original_default = original.default_value(param_name)
- except astroid.exceptions.NoDefault:
- original_default = default_missing
- try:
- overridden_default = overridden.default_value(param_name)
- except astroid.exceptions.NoDefault:
- overridden_default = default_missing
-
- default_list = [
- arg == default_missing for arg in (original_default, overridden_default)
- ]
- if any(default_list) and not all(default_list):
- # Only one arg has no default value
- return True
-
- astroid_type_compared_attr = {
- astroid.Const: "value",
- astroid.ClassDef: "name",
- astroid.Tuple: "elts",
- astroid.List: "elts",
- }
- handled_types = tuple(
- astroid_type for astroid_type in astroid_type_compared_attr
- )
- original_type = _get_node_type(original_default, handled_types)
- if original_type:
- #  We handle only astroid types that are inside the dict astroid_type_compared_attr
- if not isinstance(overridden_default, original_type):
- #  Two args with same name but different types
- return True
- if not _check_arg_equality(
- original_default,
- overridden_default,
- astroid_type_compared_attr[original_type],
- ):
- # Two args with same type but different values
- return True
- return False
-
-
-def _has_different_parameters(original, overridden, dummy_parameter_regex):
- zipped = zip_longest(original, overridden)
- for original_param, overridden_param in zipped:
- params = (original_param, overridden_param)
- if not all(params):
- return True
-
- names = [param.name for param in params]
- if any(map(dummy_parameter_regex.match, names)):
- continue
- if original_param.name != overridden_param.name:
- return True
- return False
-
-
-def _different_parameters(original, overridden, dummy_parameter_regex):
- """Determine if the two methods have different parameters
-
- They are considered to have different parameters if:
-
- * they have different positional parameters, including different names
-
- * one of the methods is having variadics, while the other is not
-
- * they have different keyword only parameters.
-
- """
- original_parameters = _positional_parameters(original)
- overridden_parameters = _positional_parameters(overridden)
-
- different_positional = _has_different_parameters(
- original_parameters, overridden_parameters, dummy_parameter_regex
- )
- different_kwonly = _has_different_parameters(
- original.args.kwonlyargs, overridden.args.kwonlyargs, dummy_parameter_regex
- )
- if original.name in PYMETHODS:
- # Ignore the difference for special methods. If the parameter
- # numbers are different, then that is going to be caught by
- # unexpected-special-method-signature.
- # If the names are different, it doesn't matter, since they can't
- # be used as keyword arguments anyway.
- different_positional = different_kwonly = False
-
- # Both or none should have extra variadics, otherwise the method
- # loses or gains capabilities that are not reflected into the parent method,
- # leading to potential inconsistencies in the code.
- different_kwarg = (
- sum(1 for param in (original.args.kwarg, overridden.args.kwarg) if not param)
- == 1
- )
- different_vararg = (
- sum(1 for param in (original.args.vararg, overridden.args.vararg) if not param)
- == 1
- )
-
- return any(
- (different_positional, different_kwarg, different_vararg, different_kwonly)
- )
-
-
-def _is_invalid_base_class(cls):
- return cls.name in INVALID_BASE_CLASSES and is_builtin_object(cls)
-
-
-def _has_data_descriptor(cls, attr):
- attributes = cls.getattr(attr)
- for attribute in attributes:
- try:
- for inferred in attribute.infer():
- if isinstance(inferred, astroid.Instance):
- try:
- inferred.getattr("__get__")
- inferred.getattr("__set__")
- except astroid.NotFoundError:
- continue
- else:
- return True
- except astroid.InferenceError:
- # Can't infer, avoid emitting a false positive in this case.
- return True
- return False
-
-
-def _called_in_methods(func, klass, methods):
- """ Check if the func was called in any of the given methods,
- belonging to the *klass*. Returns True if so, False otherwise.
- """
- if not isinstance(func, astroid.FunctionDef):
- return False
- for method in methods:
- try:
- inferred = klass.getattr(method)
- except astroid.NotFoundError:
- continue
- for infer_method in inferred:
- for call in infer_method.nodes_of_class(astroid.Call):
- try:
- bound = next(call.func.infer())
- except (astroid.InferenceError, StopIteration):
- continue
- if not isinstance(bound, astroid.BoundMethod):
- continue
- func_obj = bound._proxied
- if isinstance(func_obj, astroid.UnboundMethod):
- func_obj = func_obj._proxied
- if func_obj.name == func.name:
- return True
- return False
-
-
-def _is_attribute_property(name, klass):
- """ Check if the given attribute *name* is a property
- in the given *klass*.
-
- It will look for `property` calls or for functions
- with the given name, decorated by `property` or `property`
- subclasses.
- Returns ``True`` if the name is a property in the given klass,
- ``False`` otherwise.
- """
-
- try:
- attributes = klass.getattr(name)
- except astroid.NotFoundError:
- return False
- property_name = "{}.property".format(BUILTINS)
- for attr in attributes:
- if attr is astroid.Uninferable:
- continue
- try:
- inferred = next(attr.infer())
- except astroid.InferenceError:
- continue
- if isinstance(inferred, astroid.FunctionDef) and decorated_with_property(
- inferred
- ):
- return True
- if inferred.pytype() == property_name:
- return True
- return False
-
-
-def _has_bare_super_call(fundef_node):
- for call in fundef_node.nodes_of_class(astroid.Call):
- func = call.func
- if isinstance(func, astroid.Name) and func.name == "super" and not call.args:
- return True
- return False
-
-
-def _safe_infer_call_result(node, caller, context=None):
- """
- Safely infer the return value of a function.
-
- Returns None if inference failed or if there is some ambiguity (more than
- one node has been inferred). Otherwise returns inferred value.
- """
- try:
- inferit = node.infer_call_result(caller, context=context)
- value = next(inferit)
- except astroid.InferenceError:
- return None # inference failed
- except StopIteration:
- return None # no values inferred
- try:
- next(inferit)
- return None # there is ambiguity on the inferred node
- except astroid.InferenceError:
- return None # there is some kind of ambiguity
- except StopIteration:
- return value
-
-
-def _has_same_layout_slots(slots, assigned_value):
- inferred = next(assigned_value.infer())
- if isinstance(inferred, astroid.ClassDef):
- other_slots = inferred.slots()
- if all(
- first_slot and second_slot and first_slot.value == second_slot.value
- for (first_slot, second_slot) in zip_longest(slots, other_slots)
- ):
- return True
- return False
-
-
-MSGS = {
- "F0202": (
- "Unable to check methods signature (%s / %s)",
- "method-check-failed",
- "Used when Pylint has been unable to check methods signature "
- "compatibility for an unexpected reason. Please report this kind "
- "if you don't make sense of it.",
- ),
- "E0202": (
- "An attribute defined in %s line %s hides this method",
- "method-hidden",
- "Used when a class defines a method which is hidden by an "
- "instance attribute from an ancestor class or set by some "
- "client code.",
- ),
- "E0203": (
- "Access to member %r before its definition line %s",
- "access-member-before-definition",
- "Used when an instance member is accessed before it's actually assigned.",
- ),
- "W0201": (
- "Attribute %r defined outside __init__",
- "attribute-defined-outside-init",
- "Used when an instance attribute is defined outside the __init__ method.",
- ),
- "W0212": (
- "Access to a protected member %s of a client class", # E0214
- "protected-access",
- "Used when a protected member (i.e. class member with a name "
- "beginning with an underscore) is access outside the class or a "
- "descendant of the class where it's defined.",
- ),
- "E0211": (
- "Method has no argument",
- "no-method-argument",
- "Used when a method which should have the bound instance as "
- "first argument has no argument defined.",
- ),
- "E0213": (
- 'Method should have "self" as first argument',
- "no-self-argument",
- 'Used when a method has an attribute different the "self" as '
- "first argument. This is considered as an error since this is "
- "a so common convention that you shouldn't break it!",
- ),
- "C0202": (
- "Class method %s should have %s as first argument",
- "bad-classmethod-argument",
- "Used when a class method has a first argument named differently "
- "than the value specified in valid-classmethod-first-arg option "
- '(default to "cls"), recommended to easily differentiate them '
- "from regular instance methods.",
- ),
- "C0203": (
- "Metaclass method %s should have %s as first argument",
- "bad-mcs-method-argument",
- "Used when a metaclass method has a first argument named "
- "differently than the value specified in valid-classmethod-first"
- '-arg option (default to "cls"), recommended to easily '
- "differentiate them from regular instance methods.",
- ),
- "C0204": (
- "Metaclass class method %s should have %s as first argument",
- "bad-mcs-classmethod-argument",
- "Used when a metaclass class method has a first argument named "
- "differently than the value specified in valid-metaclass-"
- 'classmethod-first-arg option (default to "mcs"), recommended to '
- "easily differentiate them from regular instance methods.",
- ),
- "W0211": (
- "Static method with %r as first argument",
- "bad-staticmethod-argument",
- 'Used when a static method has "self" or a value specified in '
- "valid-classmethod-first-arg option or "
- "valid-metaclass-classmethod-first-arg option as first argument.",
- ),
- "R0201": (
- "Method could be a function",
- "no-self-use",
- "Used when a method doesn't use its bound instance, and so could "
- "be written as a function.",
- ),
- "W0221": (
- "Parameters differ from %s %r method",
- "arguments-differ",
- "Used when a method has a different number of arguments than in "
- "the implemented interface or in an overridden method.",
- ),
- "W0222": (
- "Signature differs from %s %r method",
- "signature-differs",
- "Used when a method signature is different than in the "
- "implemented interface or in an overridden method.",
- ),
- "W0223": (
- "Method %r is abstract in class %r but is not overridden",
- "abstract-method",
- "Used when an abstract method (i.e. raise NotImplementedError) is "
- "not overridden in concrete class.",
- ),
- "W0231": (
- "__init__ method from base class %r is not called",
- "super-init-not-called",
- "Used when an ancestor class method has an __init__ method "
- "which is not called by a derived class.",
- ),
- "W0232": (
- "Class has no __init__ method",
- "no-init",
- "Used when a class has no __init__ method, neither its parent classes.",
- ),
- "W0233": (
- "__init__ method from a non direct base class %r is called",
- "non-parent-init-called",
- "Used when an __init__ method is called on a class which is not "
- "in the direct ancestors for the analysed class.",
- ),
- "W0235": (
- "Useless super delegation in method %r",
- "useless-super-delegation",
- "Used whenever we can detect that an overridden method is useless, "
- "relying on super() delegation to do the same thing as another method "
- "from the MRO.",
- ),
- "W0236": (
- "Method %r was expected to be %r, found it instead as %r",
- "invalid-overridden-method",
- "Used when we detect that a method was overridden as a property "
- "or the other way around, which could result in potential bugs at "
- "runtime.",
- ),
- "E0236": (
- "Invalid object %r in __slots__, must contain only non empty strings",
- "invalid-slots-object",
- "Used when an invalid (non-string) object occurs in __slots__.",
- ),
- "E0237": (
- "Assigning to attribute %r not defined in class slots",
- "assigning-non-slot",
- "Used when assigning to an attribute not defined in the class slots.",
- ),
- "E0238": (
- "Invalid __slots__ object",
- "invalid-slots",
- "Used when an invalid __slots__ is found in class. "
- "Only a string, an iterable or a sequence is permitted.",
- ),
- "E0239": (
- "Inheriting %r, which is not a class.",
- "inherit-non-class",
- "Used when a class inherits from something which is not a class.",
- ),
- "E0240": (
- "Inconsistent method resolution order for class %r",
- "inconsistent-mro",
- "Used when a class has an inconsistent method resolution order.",
- ),
- "E0241": (
- "Duplicate bases for class %r",
- "duplicate-bases",
- "Used when a class has duplicate bases.",
- ),
- "E0242": (
- "Value %r in slots conflicts with class variable",
- "class-variable-slots-conflict",
- "Used when a value in __slots__ conflicts with a class variable, property or method.",
- ),
- "R0202": (
- "Consider using a decorator instead of calling classmethod",
- "no-classmethod-decorator",
- "Used when a class method is defined without using the decorator syntax.",
- ),
- "R0203": (
- "Consider using a decorator instead of calling staticmethod",
- "no-staticmethod-decorator",
- "Used when a static method is defined without using the decorator syntax.",
- ),
- "C0205": (
- "Class __slots__ should be a non-string iterable",
- "single-string-used-for-slots",
- "Used when a class __slots__ is a simple string, rather than an iterable.",
- ),
- "R0205": (
- "Class %r inherits from object, can be safely removed from bases in python3",
- "useless-object-inheritance",
- "Used when a class inherit from object, which under python3 is implicit, "
- "hence can be safely removed from bases.",
- ),
- "R0206": (
- "Cannot have defined parameters for properties",
- "property-with-parameters",
- "Used when we detect that a property also has parameters, which are useless, "
- "given that properties cannot be called with additional arguments.",
- ),
-}
-
-
-class ScopeAccessMap:
- """Store the accessed variables per scope."""
-
- def __init__(self):
- self._scopes = collections.defaultdict(lambda: collections.defaultdict(list))
-
- def set_accessed(self, node):
- """Set the given node as accessed."""
-
- frame = node_frame_class(node)
- if frame is None:
- # The node does not live in a class.
- return
- self._scopes[frame][node.attrname].append(node)
-
- def accessed(self, scope):
- """Get the accessed variables for the given scope."""
- return self._scopes.get(scope, {})
-
-
-class ClassChecker(BaseChecker):
- """checks for :
- * methods without self as first argument
- * overridden methods signature
- * access only to existent members via self
- * attributes not defined in the __init__ method
- * unreachable code
- """
-
- __implements__ = (IAstroidChecker,)
-
- # configuration section name
- name = "classes"
- # messages
- msgs = MSGS
- priority = -2
- # configuration options
- options = (
- (
- "defining-attr-methods",
- {
- "default": ("__init__", "__new__", "setUp", "__post_init__"),
- "type": "csv",
- "metavar": "<method names>",
- "help": "List of method names used to declare (i.e. assign) \
-instance attributes.",
- },
- ),
- (
- "valid-classmethod-first-arg",
- {
- "default": ("cls",),
- "type": "csv",
- "metavar": "<argument names>",
- "help": "List of valid names for the first argument in \
-a class method.",
- },
- ),
- (
- "valid-metaclass-classmethod-first-arg",
- {
- "default": ("cls",),
- "type": "csv",
- "metavar": "<argument names>",
- "help": "List of valid names for the first argument in \
-a metaclass class method.",
- },
- ),
- (
- "exclude-protected",
- {
- "default": (
- # namedtuple public API.
- "_asdict",
- "_fields",
- "_replace",
- "_source",
- "_make",
- ),
- "type": "csv",
- "metavar": "<protected access exclusions>",
- "help": (
- "List of member names, which should be excluded "
- "from the protected access warning."
- ),
- },
- ),
- )
-
- def __init__(self, linter=None):
- BaseChecker.__init__(self, linter)
- self._accessed = ScopeAccessMap()
- self._first_attrs = []
- self._meth_could_be_func = None
-
- @decorators.cachedproperty
- def _dummy_rgx(self):
- return get_global_option(self, "dummy-variables-rgx", default=None)
-
- @decorators.cachedproperty
- def _ignore_mixin(self):
- return get_global_option(self, "ignore-mixin-members", default=True)
-
- @check_messages(
- "abstract-method",
- "no-init",
- "invalid-slots",
- "single-string-used-for-slots",
- "invalid-slots-object",
- "class-variable-slots-conflict",
- "inherit-non-class",
- "useless-object-inheritance",
- "inconsistent-mro",
- "duplicate-bases",
- )
- def visit_classdef(self, node):
- """init visit variable _accessed
- """
- self._check_bases_classes(node)
- # if not an exception or a metaclass
- if node.type == "class" and has_known_bases(node):
- try:
- node.local_attr("__init__")
- except astroid.NotFoundError:
- self.add_message("no-init", args=node, node=node)
- self._check_slots(node)
- self._check_proper_bases(node)
- self._check_consistent_mro(node)
-
- def _check_consistent_mro(self, node):
- """Detect that a class has a consistent mro or duplicate bases."""
- try:
- node.mro()
- except InconsistentMroError:
- self.add_message("inconsistent-mro", args=node.name, node=node)
- except DuplicateBasesError:
- self.add_message("duplicate-bases", args=node.name, node=node)
- except NotImplementedError:
- # Old style class, there's no mro so don't do anything.
- pass
-
- def _check_proper_bases(self, node):
- """
- Detect that a class inherits something which is not
- a class or a type.
- """
- for base in node.bases:
- ancestor = safe_infer(base)
- if ancestor in (astroid.Uninferable, None):
- continue
- if isinstance(ancestor, astroid.Instance) and ancestor.is_subtype_of(
- "%s.type" % (BUILTINS,)
- ):
- continue
-
- if not isinstance(ancestor, astroid.ClassDef) or _is_invalid_base_class(
- ancestor
- ):
- self.add_message("inherit-non-class", args=base.as_string(), node=node)
-
- if ancestor.name == object.__name__:
- self.add_message(
- "useless-object-inheritance", args=node.name, node=node
- )
-
- def leave_classdef(self, cnode):
- """close a class node:
- check that instance attributes are defined in __init__ and check
- access to existent members
- """
- # check access to existent members on non metaclass classes
- if self._ignore_mixin and cnode.name[-5:].lower() == "mixin":
- # We are in a mixin class. No need to try to figure out if
- # something is missing, since it is most likely that it will
- # miss.
- return
-
- accessed = self._accessed.accessed(cnode)
- if cnode.type != "metaclass":
- self._check_accessed_members(cnode, accessed)
- # checks attributes are defined in an allowed method such as __init__
- if not self.linter.is_message_enabled("attribute-defined-outside-init"):
- return
- defining_methods = self.config.defining_attr_methods
- current_module = cnode.root()
- for attr, nodes in cnode.instance_attrs.items():
- # Exclude `__dict__` as it is already defined.
- if attr == "__dict__":
- continue
-
- # Skip nodes which are not in the current module and it may screw up
- # the output, while it's not worth it
- nodes = [
- n
- for n in nodes
- if not isinstance(n.statement(), (astroid.Delete, astroid.AugAssign))
- and n.root() is current_module
- ]
- if not nodes:
- continue # error detected by typechecking
-
- # Check if any method attr is defined in is a defining method
- # or if we have the attribute defined in a setter.
- frames = (node.frame() for node in nodes)
- if any(
- frame.name in defining_methods or is_property_setter(frame)
- for frame in frames
- ):
- continue
-
- # check attribute is defined in a parent's __init__
- for parent in cnode.instance_attr_ancestors(attr):
- attr_defined = False
- # check if any parent method attr is defined in is a defining method
- for node in parent.instance_attrs[attr]:
- if node.frame().name in defining_methods:
- attr_defined = True
- if attr_defined:
- # we're done :)
- break
- else:
- # check attribute is defined as a class attribute
- try:
- cnode.local_attr(attr)
- except astroid.NotFoundError:
- for node in nodes:
- if node.frame().name not in defining_methods:
- # If the attribute was set by a call in any
- # of the defining methods, then don't emit
- # the warning.
- if _called_in_methods(
- node.frame(), cnode, defining_methods
- ):
- continue
- self.add_message(
- "attribute-defined-outside-init", args=attr, node=node
- )
-
- def visit_functiondef(self, node):
- """check method arguments, overriding"""
- # ignore actual functions
- if not node.is_method():
- return
-
- self._check_useless_super_delegation(node)
- self._check_property_with_parameters(node)
-
- klass = node.parent.frame()
- self._meth_could_be_func = True
- # check first argument is self if this is actually a method
- self._check_first_arg_for_type(node, klass.type == "metaclass")
- if node.name == "__init__":
- self._check_init(node)
- return
- # check signature if the method overloads inherited method
- for overridden in klass.local_attr_ancestors(node.name):
- # get astroid for the searched method
- try:
- parent_function = overridden[node.name]
- except KeyError:
- # we have found the method but it's not in the local
- # dictionary.
- # This may happen with astroid build from living objects
- continue
- if not isinstance(parent_function, astroid.FunctionDef):
- continue
- self._check_signature(node, parent_function, "overridden", klass)
- self._check_invalid_overridden_method(node, parent_function)
- break
-
- if node.decorators:
- for decorator in node.decorators.nodes:
- if isinstance(decorator, astroid.Attribute) and decorator.attrname in (
- "getter",
- "setter",
- "deleter",
- ):
- # attribute affectation will call this method, not hiding it
- return
- if isinstance(decorator, astroid.Name):
- if decorator.name == "property":
- # attribute affectation will either call a setter or raise
- # an attribute error, anyway not hiding the function
- return
-
- # Infer the decorator and see if it returns something useful
- inferred = safe_infer(decorator)
- if not inferred:
- return
- if isinstance(inferred, astroid.FunctionDef):
- # Okay, it's a decorator, let's see what it can infer.
- try:
- inferred = next(inferred.infer_call_result(inferred))
- except astroid.InferenceError:
- return
- try:
- if (
- isinstance(inferred, (astroid.Instance, astroid.ClassDef))
- and inferred.getattr("__get__")
- and inferred.getattr("__set__")
- ):
- return
- except astroid.AttributeInferenceError:
- pass
-
- # check if the method is hidden by an attribute
- try:
- overridden = klass.instance_attr(node.name)[0]
- overridden_frame = overridden.frame()
- if (
- isinstance(overridden_frame, astroid.FunctionDef)
- and overridden_frame.type == "method"
- ):
- overridden_frame = overridden_frame.parent.frame()
- if isinstance(overridden_frame, astroid.ClassDef) and klass.is_subtype_of(
- overridden_frame.qname()
- ):
- args = (overridden.root().name, overridden.fromlineno)
- self.add_message("method-hidden", args=args, node=node)
- except astroid.NotFoundError:
- pass
-
- visit_asyncfunctiondef = visit_functiondef
-
- def _check_useless_super_delegation(self, function):
- """Check if the given function node is an useless method override
-
- We consider it *useless* if it uses the super() builtin, but having
- nothing additional whatsoever than not implementing the method at all.
- If the method uses super() to delegate an operation to the rest of the MRO,
- and if the method called is the same as the current one, the arguments
- passed to super() are the same as the parameters that were passed to
- this method, then the method could be removed altogether, by letting
- other implementation to take precedence.
- """
-
- if (
- not function.is_method()
- # With decorators is a change of use
- or function.decorators
- ):
- return
-
- body = function.body
- if len(body) != 1:
- # Multiple statements, which means this overridden method
- # could do multiple things we are not aware of.
- return
-
- statement = body[0]
- if not isinstance(statement, (astroid.Expr, astroid.Return)):
- # Doing something else than what we are interested into.
- return
-
- call = statement.value
- if (
- not isinstance(call, astroid.Call)
- # Not a super() attribute access.
- or not isinstance(call.func, astroid.Attribute)
- ):
- return
-
- # Should be a super call.
- try:
- super_call = next(call.func.expr.infer())
- except astroid.InferenceError:
- return
- else:
- if not isinstance(super_call, objects.Super):
- return
-
- # The name should be the same.
- if call.func.attrname != function.name:
- return
-
- # Should be a super call with the MRO pointer being the
- # current class and the type being the current instance.
- current_scope = function.parent.scope()
- if (
- super_call.mro_pointer != current_scope
- or not isinstance(super_call.type, astroid.Instance)
- or super_call.type.name != current_scope.name
- ):
- return
-
- #  Check values of default args
- klass = function.parent.frame()
- meth_node = None
- for overridden in klass.local_attr_ancestors(function.name):
- # get astroid for the searched method
- try:
- meth_node = overridden[function.name]
- except KeyError:
- # we have found the method but it's not in the local
- # dictionary.
- # This may happen with astroid build from living objects
- continue
- if (
- not isinstance(meth_node, astroid.FunctionDef)
- # If the method have an ancestor which is not a
- # function then it is legitimate to redefine it
- or _has_different_parameters_default_value(
- meth_node.args, function.args
- )
- ):
- return
- break
-
- # Detect if the parameters are the same as the call's arguments.
- params = _signature_from_arguments(function.args)
- args = _signature_from_call(call)
-
- if meth_node is not None:
-
- def form_annotations(annotations):
- return [
- annotation.as_string() for annotation in filter(None, annotations)
- ]
-
- called_annotations = form_annotations(function.args.annotations)
- overridden_annotations = form_annotations(meth_node.args.annotations)
- if called_annotations and overridden_annotations:
- if called_annotations != overridden_annotations:
- return
-
- if _definition_equivalent_to_call(params, args):
- self.add_message(
- "useless-super-delegation", node=function, args=(function.name,)
- )
-
- def _check_property_with_parameters(self, node):
- if node.args.args and len(node.args.args) > 1 and decorated_with_property(node):
- self.add_message("property-with-parameters", node=node)
-
- def _check_invalid_overridden_method(self, function_node, parent_function_node):
- parent_is_property = decorated_with_property(
- parent_function_node
- ) or is_property_setter_or_deleter(parent_function_node)
- current_is_property = decorated_with_property(
- function_node
- ) or is_property_setter_or_deleter(function_node)
- if parent_is_property and not current_is_property:
- self.add_message(
- "invalid-overridden-method",
- args=(function_node.name, "property", function_node.type),
- node=function_node,
- )
- elif not parent_is_property and current_is_property:
- self.add_message(
- "invalid-overridden-method",
- args=(function_node.name, "method", "property"),
- node=function_node,
- )
-
- def _check_slots(self, node):
- if "__slots__" not in node.locals:
- return
- for slots in node.igetattr("__slots__"):
- # check if __slots__ is a valid type
- if slots is astroid.Uninferable:
- continue
- if not is_iterable(slots) and not is_comprehension(slots):
- self.add_message("invalid-slots", node=node)
- continue
-
- if isinstance(slots, astroid.Const):
- # a string, ignore the following checks
- self.add_message("single-string-used-for-slots", node=node)
- continue
- if not hasattr(slots, "itered"):
- # we can't obtain the values, maybe a .deque?
- continue
-
- if isinstance(slots, astroid.Dict):
- values = [item[0] for item in slots.items]
- else:
- values = slots.itered()
- if values is astroid.Uninferable:
- return
- for elt in values:
- try:
- self._check_slots_elt(elt, node)
- except astroid.InferenceError:
- continue
-
- def _check_slots_elt(self, elt, node):
- for inferred in elt.infer():
- if inferred is astroid.Uninferable:
- continue
- if not isinstance(inferred, astroid.Const) or not isinstance(
- inferred.value, str
- ):
- self.add_message(
- "invalid-slots-object", args=inferred.as_string(), node=elt
- )
- continue
- if not inferred.value:
- self.add_message(
- "invalid-slots-object", args=inferred.as_string(), node=elt
- )
-
- # Check if we have a conflict with a class variable.
- class_variable = node.locals.get(inferred.value)
- if class_variable:
- # Skip annotated assignments which don't conflict at all with slots.
- if len(class_variable) == 1:
- parent = class_variable[0].parent
- if isinstance(parent, astroid.AnnAssign) and parent.value is None:
- return
- self.add_message(
- "class-variable-slots-conflict", args=(inferred.value,), node=elt
- )
-
- def leave_functiondef(self, node):
- """on method node, check if this method couldn't be a function
-
- ignore class, static and abstract methods, initializer,
- methods overridden from a parent class.
- """
- if node.is_method():
- if node.args.args is not None:
- self._first_attrs.pop()
- if not self.linter.is_message_enabled("no-self-use"):
- return
- class_node = node.parent.frame()
- if (
- self._meth_could_be_func
- and node.type == "method"
- and node.name not in PYMETHODS
- and not (
- node.is_abstract()
- or overrides_a_method(class_node, node.name)
- or decorated_with_property(node)
- or _has_bare_super_call(node)
- or is_protocol_class(class_node)
- )
- ):
- self.add_message("no-self-use", node=node)
-
- def visit_attribute(self, node):
- """check if the getattr is an access to a class member
- if so, register it. Also check for access to protected
- class member from outside its class (but ignore __special__
- methods)
- """
- # Check self
- if self._uses_mandatory_method_param(node):
- self._accessed.set_accessed(node)
- return
- if not self.linter.is_message_enabled("protected-access"):
- return
-
- self._check_protected_attribute_access(node)
-
- def visit_assignattr(self, node):
- if isinstance(
- node.assign_type(), astroid.AugAssign
- ) and self._uses_mandatory_method_param(node):
- self._accessed.set_accessed(node)
- self._check_in_slots(node)
-
- def _check_in_slots(self, node):
- """ Check that the given AssignAttr node
- is defined in the class slots.
- """
- inferred = safe_infer(node.expr)
- if not isinstance(inferred, astroid.Instance):
- return
-
- klass = inferred._proxied
- if not has_known_bases(klass):
- return
- if "__slots__" not in klass.locals or not klass.newstyle:
- return
-
- slots = klass.slots()
- if slots is None:
- return
- # If any ancestor doesn't use slots, the slots
- # defined for this class are superfluous.
- if any(
- "__slots__" not in ancestor.locals and ancestor.name != "object"
- for ancestor in klass.ancestors()
- ):
- return
-
- if not any(slot.value == node.attrname for slot in slots):
- # If we have a '__dict__' in slots, then
- # assigning any name is valid.
- if not any(slot.value == "__dict__" for slot in slots):
- if _is_attribute_property(node.attrname, klass):
- # Properties circumvent the slots mechanism,
- # so we should not emit a warning for them.
- return
- if node.attrname in klass.locals and _has_data_descriptor(
- klass, node.attrname
- ):
- # Descriptors circumvent the slots mechanism as well.
- return
- if node.attrname == "__class__" and _has_same_layout_slots(
- slots, node.parent.value
- ):
- return
- self.add_message("assigning-non-slot", args=(node.attrname,), node=node)
-
- @check_messages(
- "protected-access", "no-classmethod-decorator", "no-staticmethod-decorator"
- )
- def visit_assign(self, assign_node):
- self._check_classmethod_declaration(assign_node)
- node = assign_node.targets[0]
- if not isinstance(node, astroid.AssignAttr):
- return
-
- if self._uses_mandatory_method_param(node):
- return
- self._check_protected_attribute_access(node)
-
- def _check_classmethod_declaration(self, node):
- """Checks for uses of classmethod() or staticmethod()
-
- When a @classmethod or @staticmethod decorator should be used instead.
- A message will be emitted only if the assignment is at a class scope
- and only if the classmethod's argument belongs to the class where it
- is defined.
- `node` is an assign node.
- """
- if not isinstance(node.value, astroid.Call):
- return
-
- # check the function called is "classmethod" or "staticmethod"
- func = node.value.func
- if not isinstance(func, astroid.Name) or func.name not in (
- "classmethod",
- "staticmethod",
- ):
- return
-
- msg = (
- "no-classmethod-decorator"
- if func.name == "classmethod"
- else "no-staticmethod-decorator"
- )
- # assignment must be at a class scope
- parent_class = node.scope()
- if not isinstance(parent_class, astroid.ClassDef):
- return
-
- # Check if the arg passed to classmethod is a class member
- classmeth_arg = node.value.args[0]
- if not isinstance(classmeth_arg, astroid.Name):
- return
-
- method_name = classmeth_arg.name
- if any(method_name == member.name for member in parent_class.mymethods()):
- self.add_message(msg, node=node.targets[0])
-
- def _check_protected_attribute_access(self, node):
- """Given an attribute access node (set or get), check if attribute
- access is legitimate. Call _check_first_attr with node before calling
- this method. Valid cases are:
- * self._attr in a method or cls._attr in a classmethod. Checked by
- _check_first_attr.
- * Klass._attr inside "Klass" class.
- * Klass2._attr inside "Klass" class when Klass2 is a base class of
- Klass.
- """
- attrname = node.attrname
-
- if (
- is_attr_protected(attrname)
- and attrname not in self.config.exclude_protected
- ):
-
- klass = node_frame_class(node)
-
- # In classes, check we are not getting a parent method
- # through the class object or through super
- callee = node.expr.as_string()
-
- # We are not in a class, no remaining valid case
- if klass is None:
- self.add_message("protected-access", node=node, args=attrname)
- return
-
- # If the expression begins with a call to super, that's ok.
- if (
- isinstance(node.expr, astroid.Call)
- and isinstance(node.expr.func, astroid.Name)
- and node.expr.func.name == "super"
- ):
- return
-
- # If the expression begins with a call to type(self), that's ok.
- if self._is_type_self_call(node.expr):
- return
-
- # We are in a class, one remaining valid cases, Klass._attr inside
- # Klass
- if not (callee == klass.name or callee in klass.basenames):
- # Detect property assignments in the body of the class.
- # This is acceptable:
- #
- # class A:
- # b = property(lambda: self._b)
-
- stmt = node.parent.statement()
- if (
- isinstance(stmt, astroid.Assign)
- and len(stmt.targets) == 1
- and isinstance(stmt.targets[0], astroid.AssignName)
- ):
- name = stmt.targets[0].name
- if _is_attribute_property(name, klass):
- return
-
- #  A licit use of protected member is inside a special method
- if not attrname.startswith(
- "__"
- ) and self._is_called_inside_special_method(node):
- return
-
- self.add_message("protected-access", node=node, args=attrname)
-
- @staticmethod
- def _is_called_inside_special_method(node: astroid.node_classes.NodeNG) -> bool:
- """
- Returns true if the node is located inside a special (aka dunder) method
- """
- try:
- frame_name = node.frame().name
- except AttributeError:
- return False
- return frame_name and frame_name in PYMETHODS
-
- def _is_type_self_call(self, expr):
- return (
- isinstance(expr, astroid.Call)
- and isinstance(expr.func, astroid.Name)
- and expr.func.name == "type"
- and len(expr.args) == 1
- and self._is_mandatory_method_param(expr.args[0])
- )
-
- def visit_name(self, node):
- """check if the name handle an access to a class member
- if so, register it
- """
- if self._first_attrs and (
- node.name == self._first_attrs[-1] or not self._first_attrs[-1]
- ):
- self._meth_could_be_func = False
-
- def _check_accessed_members(self, node, accessed):
- """check that accessed members are defined"""
- excs = ("AttributeError", "Exception", "BaseException")
- for attr, nodes in accessed.items():
- try:
- # is it a class attribute ?
- node.local_attr(attr)
- # yes, stop here
- continue
- except astroid.NotFoundError:
- pass
- # is it an instance attribute of a parent class ?
- try:
- next(node.instance_attr_ancestors(attr))
- # yes, stop here
- continue
- except StopIteration:
- pass
- # is it an instance attribute ?
- try:
- defstmts = node.instance_attr(attr)
- except astroid.NotFoundError:
- pass
- else:
- # filter out augment assignment nodes
- defstmts = [stmt for stmt in defstmts if stmt not in nodes]
- if not defstmts:
- # only augment assignment for this node, no-member should be
- # triggered by the typecheck checker
- continue
- # filter defstmts to only pick the first one when there are
- # several assignments in the same scope
- scope = defstmts[0].scope()
- defstmts = [
- stmt
- for i, stmt in enumerate(defstmts)
- if i == 0 or stmt.scope() is not scope
- ]
- # if there are still more than one, don't attempt to be smarter
- # than we can be
- if len(defstmts) == 1:
- defstmt = defstmts[0]
- # check that if the node is accessed in the same method as
- # it's defined, it's accessed after the initial assignment
- frame = defstmt.frame()
- lno = defstmt.fromlineno
- for _node in nodes:
- if (
- _node.frame() is frame
- and _node.fromlineno < lno
- and not astroid.are_exclusive(
- _node.statement(), defstmt, excs
- )
- ):
- self.add_message(
- "access-member-before-definition",
- node=_node,
- args=(attr, lno),
- )
-
- def _check_first_arg_for_type(self, node, metaclass=0):
- """check the name of first argument, expect:
-
- * 'self' for a regular method
- * 'cls' for a class method or a metaclass regular method (actually
- valid-classmethod-first-arg value)
- * 'mcs' for a metaclass class method (actually
- valid-metaclass-classmethod-first-arg)
- * not one of the above for a static method
- """
- # don't care about functions with unknown argument (builtins)
- if node.args.args is None:
- return
- if node.args.args:
- first_arg = node.argnames()[0]
- elif node.args.posonlyargs:
- first_arg = node.args.posonlyargs[0].name
- else:
- first_arg = None
- self._first_attrs.append(first_arg)
- first = self._first_attrs[-1]
- # static method
- if node.type == "staticmethod":
- if (
- first_arg == "self"
- or first_arg in self.config.valid_classmethod_first_arg
- or first_arg in self.config.valid_metaclass_classmethod_first_arg
- ):
- self.add_message("bad-staticmethod-argument", args=first, node=node)
- return
- self._first_attrs[-1] = None
- # class / regular method with no args
- elif not node.args.args and not node.args.posonlyargs:
- self.add_message("no-method-argument", node=node)
- # metaclass
- elif metaclass:
- # metaclass __new__ or classmethod
- if node.type == "classmethod":
- self._check_first_arg_config(
- first,
- self.config.valid_metaclass_classmethod_first_arg,
- node,
- "bad-mcs-classmethod-argument",
- node.name,
- )
- # metaclass regular method
- else:
- self._check_first_arg_config(
- first,
- self.config.valid_classmethod_first_arg,
- node,
- "bad-mcs-method-argument",
- node.name,
- )
- # regular class
- else:
- # class method
- if node.type == "classmethod" or node.name == "__class_getitem__":
- self._check_first_arg_config(
- first,
- self.config.valid_classmethod_first_arg,
- node,
- "bad-classmethod-argument",
- node.name,
- )
- # regular method without self as argument
- elif first != "self":
- self.add_message("no-self-argument", node=node)
-
- def _check_first_arg_config(self, first, config, node, message, method_name):
- if first not in config:
- if len(config) == 1:
- valid = repr(config[0])
- else:
- valid = ", ".join(repr(v) for v in config[:-1])
- valid = "%s or %r" % (valid, config[-1])
- self.add_message(message, args=(method_name, valid), node=node)
-
- def _check_bases_classes(self, node):
- """check that the given class node implements abstract methods from
- base classes
- """
-
- def is_abstract(method):
- return method.is_abstract(pass_is_abstract=False)
-
- # check if this class abstract
- if class_is_abstract(node):
- return
-
- methods = sorted(
- unimplemented_abstract_methods(node, is_abstract).items(),
- key=lambda item: item[0],
- )
- for name, method in methods:
- owner = method.parent.frame()
- if owner is node:
- continue
- # owner is not this class, it must be a parent class
- # check that the ancestor's method is not abstract
- if name in node.locals:
- # it is redefined as an attribute or with a descriptor
- continue
- self.add_message("abstract-method", node=node, args=(name, owner.name))
-
- def _check_init(self, node):
- """check that the __init__ method call super or ancestors'__init__
- method (unless it is used for type hinting with `typing.overload`)
- """
- if not self.linter.is_message_enabled(
- "super-init-not-called"
- ) and not self.linter.is_message_enabled("non-parent-init-called"):
- return
- klass_node = node.parent.frame()
- to_call = _ancestors_to_call(klass_node)
- not_called_yet = dict(to_call)
- for stmt in node.nodes_of_class(astroid.Call):
- expr = stmt.func
- if not isinstance(expr, astroid.Attribute) or expr.attrname != "__init__":
- continue
- # skip the test if using super
- if (
- isinstance(expr.expr, astroid.Call)
- and isinstance(expr.expr.func, astroid.Name)
- and expr.expr.func.name == "super"
- ):
- return
- try:
- for klass in expr.expr.infer():
- if klass is astroid.Uninferable:
- continue
- # The inferred klass can be super(), which was
- # assigned to a variable and the `__init__`
- # was called later.
- #
- # base = super()
- # base.__init__(...)
-
- if (
- isinstance(klass, astroid.Instance)
- and isinstance(klass._proxied, astroid.ClassDef)
- and is_builtin_object(klass._proxied)
- and klass._proxied.name == "super"
- ):
- return
- if isinstance(klass, objects.Super):
- return
- try:
- del not_called_yet[klass]
- except KeyError:
- if klass not in to_call:
- self.add_message(
- "non-parent-init-called", node=expr, args=klass.name
- )
- except astroid.InferenceError:
- continue
- for klass, method in not_called_yet.items():
- if decorated_with(node, ["typing.overload"]):
- continue
- cls = node_frame_class(method)
- if klass.name == "object" or (cls and cls.name == "object"):
- continue
- self.add_message("super-init-not-called", args=klass.name, node=node)
-
- def _check_signature(self, method1, refmethod, class_type, cls):
- """check that the signature of the two given methods match
- """
- if not (
- isinstance(method1, astroid.FunctionDef)
- and isinstance(refmethod, astroid.FunctionDef)
- ):
- self.add_message(
- "method-check-failed", args=(method1, refmethod), node=method1
- )
- return
-
- instance = cls.instantiate_class()
- method1 = function_to_method(method1, instance)
- refmethod = function_to_method(refmethod, instance)
-
- # Don't care about functions with unknown argument (builtins).
- if method1.args.args is None or refmethod.args.args is None:
- return
-
- # Ignore private to class methods.
- if is_attr_private(method1.name):
- return
- # Ignore setters, they have an implicit extra argument,
- # which shouldn't be taken in consideration.
- if is_property_setter(method1):
- return
-
- if _different_parameters(
- refmethod, method1, dummy_parameter_regex=self._dummy_rgx
- ):
- self.add_message(
- "arguments-differ", args=(class_type, method1.name), node=method1
- )
- elif len(method1.args.defaults) < len(refmethod.args.defaults):
- self.add_message(
- "signature-differs", args=(class_type, method1.name), node=method1
- )
-
- def _uses_mandatory_method_param(self, node):
- """Check that attribute lookup name use first attribute variable name
-
- Name is `self` for method, `cls` for classmethod and `mcs` for metaclass.
- """
- return self._is_mandatory_method_param(node.expr)
-
- def _is_mandatory_method_param(self, node):
- """Check if astroid.Name corresponds to first attribute variable name
-
- Name is `self` for method, `cls` for classmethod and `mcs` for metaclass.
- """
- return (
- self._first_attrs
- and isinstance(node, astroid.Name)
- and node.name == self._first_attrs[-1]
- )
-
-
-class SpecialMethodsChecker(BaseChecker):
- """Checker which verifies that special methods
- are implemented correctly.
- """
-
- __implements__ = (IAstroidChecker,)
- name = "classes"
- msgs = {
- "E0301": (
- "__iter__ returns non-iterator",
- "non-iterator-returned",
- "Used when an __iter__ method returns something which is not an "
- "iterable (i.e. has no `%s` method)" % NEXT_METHOD,
- {
- "old_names": [
- ("W0234", "old-non-iterator-returned-1"),
- ("E0234", "old-non-iterator-returned-2"),
- ]
- },
- ),
- "E0302": (
- "The special method %r expects %s param(s), %d %s given",
- "unexpected-special-method-signature",
- "Emitted when a special method was defined with an "
- "invalid number of parameters. If it has too few or "
- "too many, it might not work at all.",
- {"old_names": [("E0235", "bad-context-manager")]},
- ),
- "E0303": (
- "__len__ does not return non-negative integer",
- "invalid-length-returned",
- "Used when a __len__ method returns something which is not a "
- "non-negative integer",
- {},
- ),
- }
- priority = -2
-
- @check_messages(
- "unexpected-special-method-signature",
- "non-iterator-returned",
- "invalid-length-returned",
- )
- def visit_functiondef(self, node):
- if not node.is_method():
- return
- if node.name == "__iter__":
- self._check_iter(node)
- if node.name == "__len__":
- self._check_len(node)
- if node.name in PYMETHODS:
- self._check_unexpected_method_signature(node)
-
- visit_asyncfunctiondef = visit_functiondef
-
- def _check_unexpected_method_signature(self, node):
- expected_params = SPECIAL_METHODS_PARAMS[node.name]
-
- if expected_params is None:
- # This can support a variable number of parameters.
- return
- if not node.args.args and not node.args.vararg:
- # Method has no parameter, will be caught
- # by no-method-argument.
- return
-
- if decorated_with(node, [BUILTINS + ".staticmethod"]):
- # We expect to not take in consideration self.
- all_args = node.args.args
- else:
- all_args = node.args.args[1:]
- mandatory = len(all_args) - len(node.args.defaults)
- optional = len(node.args.defaults)
- current_params = mandatory + optional
-
- if isinstance(expected_params, tuple):
- # The expected number of parameters can be any value from this
- # tuple, although the user should implement the method
- # to take all of them in consideration.
- emit = mandatory not in expected_params
- expected_params = "between %d or %d" % expected_params
- else:
- # If the number of mandatory parameters doesn't
- # suffice, the expected parameters for this
- # function will be deduced from the optional
- # parameters.
- rest = expected_params - mandatory
- if rest == 0:
- emit = False
- elif rest < 0:
- emit = True
- elif rest > 0:
- emit = not ((optional - rest) >= 0 or node.args.vararg)
-
- if emit:
- verb = "was" if current_params <= 1 else "were"
- self.add_message(
- "unexpected-special-method-signature",
- args=(node.name, expected_params, current_params, verb),
- node=node,
- )
-
- @staticmethod
- def _is_iterator(node):
- if node is astroid.Uninferable:
- # Just ignore Uninferable objects.
- return True
- if isinstance(node, Generator):
- # Generators can be itered.
- return True
-
- if isinstance(node, astroid.Instance):
- try:
- node.local_attr(NEXT_METHOD)
- return True
- except astroid.NotFoundError:
- pass
- elif isinstance(node, astroid.ClassDef):
- metaclass = node.metaclass()
- if metaclass and isinstance(metaclass, astroid.ClassDef):
- try:
- metaclass.local_attr(NEXT_METHOD)
- return True
- except astroid.NotFoundError:
- pass
- return False
-
- def _check_iter(self, node):
- inferred = _safe_infer_call_result(node, node)
- if inferred is not None:
- if not self._is_iterator(inferred):
- self.add_message("non-iterator-returned", node=node)
-
- def _check_len(self, node):
- inferred = _safe_infer_call_result(node, node)
- if not inferred or inferred is astroid.Uninferable:
- return
-
- if (
- isinstance(inferred, astroid.Instance)
- and inferred.name == "int"
- and not isinstance(inferred, astroid.Const)
- ):
- # Assume it's good enough, since the int() call might wrap
- # something that's uninferable for us
- return
-
- if not isinstance(inferred, astroid.Const):
- self.add_message("invalid-length-returned", node=node)
- return
-
- value = inferred.value
- if not isinstance(value, int) or value < 0:
- self.add_message("invalid-length-returned", node=node)
-
-
-def _ancestors_to_call(klass_node, method="__init__"):
- """return a dictionary where keys are the list of base classes providing
- the queried method, and so that should/may be called from the method node
- """
- to_call = {}
- for base_node in klass_node.ancestors(recurs=False):
- try:
- to_call[base_node] = next(base_node.igetattr(method))
- except astroid.InferenceError:
- continue
- return to_call
-
-
-def register(linter):
- """required method to auto register this checker """
- linter.register_checker(ClassChecker(linter))
- linter.register_checker(SpecialMethodsChecker(linter))
generated by cgit (git 2.34.1) at 2024-12-19 10:17:10 +0000