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# 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
"""check for new / old style related problems
"""
import sys
import astroid
from pylint.interfaces import IAstroidChecker, INFERENCE, INFERENCE_FAILURE, HIGH
from pylint.checkers import BaseChecker
from pylint.checkers.utils import (
check_messages,
node_frame_class,
has_known_bases
)
MSGS = {
'E1001': ('Use of __slots__ on an old style class',
'slots-on-old-class',
'Used when an old style class uses the __slots__ attribute.',
{'maxversion': (3, 0)}),
'E1002': ('Use of super on an old style class',
'super-on-old-class',
'Used when an old style class uses the super builtin.',
{'maxversion': (3, 0)}),
'E1003': ('Bad first argument %r given to super()',
'bad-super-call',
'Used when another argument than the current class is given as \
first argument of the super builtin.'),
'E1004': ('Missing argument to super()',
'missing-super-argument',
'Used when the super builtin didn\'t receive an \
argument.',
{'maxversion': (3, 0)}),
'W1001': ('Use of "property" on an old style class',
'property-on-old-class',
'Used when Pylint detect the use of the builtin "property" \
on an old style class while this is relying on new style \
classes features.',
{'maxversion': (3, 0)}),
'C1001': ('Old-style class defined.',
'old-style-class',
'Used when a class is defined that does not inherit from another '
'class and does not inherit explicitly from "object".',
{'maxversion': (3, 0)})
}
class NewStyleConflictChecker(BaseChecker):
"""checks for usage of new style capabilities on old style classes and
other new/old styles conflicts problems
* use of property, __slots__, super
* "super" usage
"""
__implements__ = (IAstroidChecker,)
# configuration section name
name = 'newstyle'
# messages
msgs = MSGS
priority = -2
# configuration options
options = ()
@check_messages('slots-on-old-class', 'old-style-class')
def visit_classdef(self, node):
""" Check __slots__ in old style classes and old
style class definition.
"""
if '__slots__' in node and not node.newstyle:
confidence = (INFERENCE if has_known_bases(node)
else INFERENCE_FAILURE)
self.add_message('slots-on-old-class', node=node,
confidence=confidence)
# The node type could be class, exception, metaclass, or
# interface. Presumably, the non-class-type nodes would always
# have an explicit base class anyway.
if not node.bases and node.type == 'class' and not node.metaclass():
# We use confidence HIGH here because this message should only ever
# be emitted for classes at the root of the inheritance hierarchyself.
self.add_message('old-style-class', node=node, confidence=HIGH)
@check_messages('property-on-old-class')
def visit_call(self, node):
"""check property usage"""
parent = node.parent.frame()
if (isinstance(parent, astroid.ClassDef) and
not parent.newstyle and
isinstance(node.func, astroid.Name)):
confidence = (INFERENCE if has_known_bases(parent)
else INFERENCE_FAILURE)
name = node.func.name
if name == 'property':
self.add_message('property-on-old-class', node=node,
confidence=confidence)
@check_messages('super-on-old-class', 'bad-super-call', 'missing-super-argument')
def visit_functiondef(self, node):
"""check use of super"""
# ignore actual functions or method within a new style class
if not node.is_method():
return
klass = node.parent.frame()
for stmt in node.nodes_of_class(astroid.Call):
if node_frame_class(stmt) != node_frame_class(node):
# Don't look down in other scopes.
continue
expr = stmt.func
if not isinstance(expr, astroid.Attribute):
continue
call = expr.expr
# skip the test if using super
if not (isinstance(call, astroid.Call) and
isinstance(call.func, astroid.Name) and
call.func.name == 'super'):
continue
if not klass.newstyle and has_known_bases(klass):
# super should not be used on an old style class
self.add_message('super-on-old-class', node=node)
else:
# super first arg should be the class
if not call.args:
if sys.version_info[0] == 3:
# unless Python 3
continue
else:
self.add_message('missing-super-argument', node=call)
continue
try:
supcls = call.args and next(call.args[0].infer(), None)
except astroid.InferenceError:
continue
if klass is not supcls:
name = None
# if supcls is not YES, then supcls was infered
# and use its name. Otherwise, try to look
# for call.args[0].name
if supcls:
name = supcls.name
elif call.args and hasattr(call.args[0], 'name'):
name = call.args[0].name
if name:
self.add_message('bad-super-call', node=call, args=(name, ))
visit_asyncfunctiondef = visit_functiondef
def register(linter):
"""required method to auto register this checker """
linter.register_checker(NewStyleConflictChecker(linter))
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