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from __future__ import absolute_import
import astroid
from pylint.checkers import BaseChecker
from pylint.interfaces import IAstroidChecker, HIGH
from pylint.checkers import utils
class Py2CompatibilityChecker(BaseChecker):
"""Verify some simple properties of code compatible with both 2 and 3"""
__implements__ = IAstroidChecker
# The name defines a custom section of the config for this checker.
name = "py2-compat"
# The priority indicates the order that pylint will run the checkers.
priority = -1
# This class variable declares the messages (ie the warnings and errors)
# that the checker can emit.
msgs = {
# Each message has a code, a message that the user will see,
# a unique symbol that identifies the message,
# and a detailed help message
# that will be included in the documentation.
"E4200": ('Use explicit inheritance from "object"',
"old-style-class",
'Python 2 requires explicit inheritance from "object"'
' for new-style classes.'),
# old-division
# "E4210": ('Use "//" for integer division or import from "__future__"',
# "division-without-import",
# 'Python 2 might perform integer division unless you import'
# ' "division" from "__future__".'),
# no-absolute-import
# "E4211": ('Always import "absolute_import" from "__future__"',
# "old-no-absolute-import",
# 'Python 2 allows relative imports unless you import'
# ' "absolute_import" from "__future__".'),
"E4212": ('Import "print_function" from "__future__"',
"print-without-import",
'Python 2 requires importing "print_function" from'
' "__future__" to use the "print()" function syntax.'),
"E4220": ('Use explicit format spec numbering',
"implicit-format-spec",
'Python 2.6 does not support implicit format spec numbering'
' "{}", use explicit numbering "{0}" or keywords "{key}".'),
"E4230": ("Use popen23.Popen with with-statements",
"with-popen23",
"Python 2 subprocess.Popen objects were not contextmanagers,"
"popen23.Popen wraps them to enable use with"
"with-statements."),
}
# This class variable declares the options
# that are configurable by the user.
options = ()
def visit_classdef(self, node):
"""Make sure classes explicitly inherit from object"""
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 hierarchy
self.add_message('old-style-class', node=node, confidence=HIGH)
def visit_call(self, node):
"""Make sure "print_function" is imported if necessary"""
if (isinstance(node.func, astroid.nodes.Name)
and node.func.name == "print"):
if "print_function" in node.root().future_imports:
def previous(node):
if node is not None:
parent = node.parent
previous = node.previous_sibling()
if previous is None:
return parent
return previous
prev = previous(node)
while prev is not None:
if (isinstance(prev, astroid.nodes.ImportFrom)
and prev.modname == "__future__"
and "print_function" in (name_alias[0] for name_alias in
prev.names)):
return
prev = previous(prev)
self.add_message("print-without-import", node=node,
confidence=HIGH)
else:
self.add_message("print-without-import", node=node,
confidence=HIGH)
func = utils.safe_infer(node.func)
if (
isinstance(func, astroid.BoundMethod)
and isinstance(func.bound, astroid.Instance)
and func.bound.name in ("str", "unicode", "bytes")
):
if func.name == "format":
if isinstance(node.func, astroid.Attribute) and not isinstance(
node.func.expr, astroid.Const
):
return
if node.starargs or node.kwargs:
return
try:
strnode = next(func.bound.infer())
except astroid.InferenceError:
return
if not (isinstance(strnode, astroid.Const) and isinstance(
strnode.value, str)):
return
try:
fields, num_args, manual_pos = (
utils.parse_format_method_string(strnode.value)
)
except utils.IncompleteFormatString:
self.add_message("bad-format-string", node=node)
if num_args != 0:
self.add_message("implicit-format-spec", node=node,
confidence=HIGH)
def visit_with(self, node):
"""Make sure subprocess.Popen objects aren't used in with-statements"""
for (cm, _) in node.items:
if isinstance(cm, astroid.nodes.Call):
if ((isinstance(cm.func, astroid.nodes.Name)
and cm.func.name.endswith("Popen")
and (node.root().scope_lookup(node.root(), "Popen")[1][0]
).modname == "subprocess")
or (isinstance(cm.func, astroid.nodes.Attribute)
and cm.func.expr == "subprocess"
and cm.func.attrname == "Popen")):
self.add_message("with-popen23", node=node, confidence=HIGH)
def register(linter):
"""This required method auto registers the checker.
:param linter: The linter to register the checker to.
:type linter: pylint.lint.PyLinter
"""
linter.register_checker(Py2CompatibilityChecker(linter))
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