diff options
Diffstat (limited to 'checkers/variables.py')
| -rw-r--r-- | checkers/variables.py | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/checkers/variables.py b/checkers/variables.py index 2ce7fcf..a6123de 100644 --- a/checkers/variables.py +++ b/checkers/variables.py @@ -146,6 +146,12 @@ MSGS = { 'Used when something which is not ' 'a sequence is used in an unpack assignment'), + 'W0640': ('Cell variable %s defined in loop', + 'cell-var-from-loop', + 'A variable used in a closure is defined in a loop. ' + 'This will result in all closures using the same value for ' + 'the closed-over variable.'), + } class VariablesChecker(BaseChecker): @@ -423,6 +429,25 @@ builtins. Remember that you should avoid to define new builtins when possible.' if default_message: self.add_message('global-statement', node=node) + def _check_late_binding_closure(self, node, assignment_node, scope_type): + node_scope = node.scope() + if not isinstance(node_scope, (astroid.Lambda, astroid.Function)): + return + + if isinstance(assignment_node, astroid.Comprehension): + if assignment_node.parent.parent_of(node.scope()): + self.add_message('cell-var-from-loop', node=node, args=node.name) + else: + assign_scope = assignment_node.scope() + maybe_for = assignment_node + while not isinstance(maybe_for, astroid.For): + if maybe_for is assign_scope: + break + maybe_for = maybe_for.parent + else: + if maybe_for.parent_of(node_scope) and not isinstance(node_scope.statement(), astroid.Return): + self.add_message('cell-var-from-loop', node=node, args=node.name) + def _loopvar_name(self, node, name): # filter variables according to node's scope # XXX used to filter parents but don't remember why, and removing this @@ -509,6 +534,8 @@ builtins. Remember that you should avoid to define new builtins when possible.' # the name has already been consumed, only check it's not a loop # variable used outside the loop if name in consumed: + defnode = assign_parent(consumed[name][0]) + self._check_late_binding_closure(node, defnode, scope_type) self._loopvar_name(node, name) break # mark the name as consumed if it's defined in this scope @@ -520,6 +547,7 @@ builtins. Remember that you should avoid to define new builtins when possible.' # checks for use before assignment defnode = assign_parent(to_consume[name][0]) if defnode is not None: + self._check_late_binding_closure(node, defnode, scope_type) defstmt = defnode.statement() defframe = defstmt.frame() maybee0601 = True |