def visit_withitem(self, node: ast.withitem) -> None:
"""Checks that we cannot create explicit unused context variables."""
if node.optional_vars:
self._check_assign_unused(
cast(ast.AST, nodes.get_parent(node)),
name_nodes.get_variables_from_node(node.optional_vars),
is_local=True,
)
self.generic_visit(node)
def check_attribute_names(self, node: ast.ClassDef) -> None:
class_attributes, _ = classes.get_attributes(
node, include_annotated=True,
)
for assign in class_attributes:
for target in get_assign_targets(assign):
for attr_name in name_nodes.get_variables_from_node(target):
self._ensure_case(assign, attr_name)
def _check_consistent_variable_return(self, node: ast.Return) -> None:
if not node.value or not self._is_named_return(node):
return
previous_node = self._get_previous_stmt(node)
if not isinstance(previous_node, AssignNodes):
return
return_names = name_nodes.get_variables_from_node(node.value)
previous_names = list(name_nodes.flat_variable_names([previous_node]))
self._check_for_violations(node, return_names, previous_names)
def visit_any_for(self, node: AnyFor) -> None:
"""Checks that we cannot create explicit unused loops."""
target_names = name_nodes.get_variables_from_node(node.target)
is_target_no_op_variable = (len(target_names) == 1
and access.is_unused(target_names[0]))
if not is_target_no_op_variable: # see issue 1406
self._check_assign_unused(
node,
target_names,
is_local=True,
)
self.generic_visit(node)
def _check_reassignment(
self,
node: AnyAssign,
names: List[str],
) -> None:
if not node.value:
return
var_values = name_nodes.get_variables_from_node(node.value)
for var_name, var_value in itertools.zip_longest(names, var_values):
if var_name == var_value:
self.add_violation(
ReassigningVariableToItselfViolation(node,
text=var_name), )
def visit_any_for(self, node: AnyFor) -> None:
"""
Checks that we cannot create explicit unused loops.
Raises:
UnusedVariableIsDefinedViolation
"""
self._check_assign_unused(
node,
name_nodes.get_variables_from_node(node.target),
is_local=True,
)
self.generic_visit(node)
def _almost_swapped(self, assigns: Sequence[ast.Assign]) -> None:
previous_var: Set[Optional[str]] = set()
for assign in assigns:
current_var = {
first(name_nodes.flat_variable_names([assign])),
first(name_nodes.get_variables_from_node(assign.value)),
}
if not all(map(bool, current_var)):
previous_var.clear()
continue
if current_var == previous_var:
self.add_violation(AlmostSwappedViolation(assign))
if len(previous_var & current_var) == 1:
current_var ^= previous_var
previous_var = current_var
def _check_reassignment(
self,
node: AnyAssign,
names: List[str],
) -> None:
if not node.value:
return
if isinstance(nodes.get_context(node), ast.ClassDef):
return # This is not a variable, but a class property
var_values = name_nodes.get_variables_from_node(node.value)
for var_name, var_value in itertools.zip_longest(names, var_values):
if var_name == var_value:
self.add_violation(
best_practices.ReassigningVariableToItselfViolation(
node,
text=var_name,
), )
def _check_reassignment(
self,
node: AnyAssign,
names: List[str],
) -> None:
if not node.value:
return
if self._is_reassignment_edge_case(node):
return
var_values = name_nodes.get_variables_from_node(node.value)
if len(names) <= 1 < len(var_values):
# It means that we have something like `x = (y, z)`
# or even `x = (x, y)`, which is also fine. See #1807
return
for var_name, var_value in itertools.zip_longest(names, var_values):
if var_name == var_value:
self.add_violation(
best_practices.ReassigningVariableToItselfViolation(
node,
text=var_name,
), )
def extract_names(node: ast.AST) -> Set[str]:
"""Extracts unique set of names from a given node."""
return set(name_nodes.get_variables_from_node(node))
def _extract_names(node: ast.AST) -> Set[str]:
return set(get_variables_from_node(node))