Refactors getattr calls and improves docs

wemake_python_styleguide/logic/exceptions.py

@@ -6,7 +6,7 @@
 
 def get_exception_name(node: ast.Raise) -> Optional[str]:
     """Returns the exception name or ``None`` if node has not it."""
-    exception = getattr(node, 'exc', None)
+    exception = node.exc
     if exception is None:
         return None
 

wemake_python_styleguide/logic/naming/name_nodes.py

@@ -28,13 +28,32 @@ def get_assigned_name(node: ast.AST) -> Optional[str]:
         return node.attr
 
     if isinstance(node, ast.ExceptHandler):
-        return getattr(node, 'name', None)
+        return node.name
 
     return None
 
 
 def flat_variable_names(nodes: Iterable[AnyAssign]) -> Iterable[str]:
-    """Returns flat variable names from several nodes."""
+    """
+    Returns flat variable names from several nodes.
+
+    Use this function when you need to get list of string variable names
+    from assign nodes.
+
+    Here's an example:
+
+    >>> import ast
+    >>> tree = ast.parse('x: int = 0')
+    >>> node = tree.body[0]
+    >>> list(flat_variable_names([node]))
+    ['x']
+
+    >>> tree = ast.parse('z = y = 0')
+    >>> node = tree.body[0]
+    >>> list(flat_variable_names([node]))
+    ['z', 'y']
+
+    """
     return itertools.chain.from_iterable((
         get_variables_from_node(target)
         for node in nodes
@@ -43,7 +62,15 @@ def flat_variable_names(nodes: Iterable[AnyAssign]) -> Iterable[str]:
 
 
 def get_variables_from_node(node: ast.AST) -> List[str]:
-    """Gets the assigned names from the list of nodes."""
+    """
+    Gets the assigned names from the list of nodes.
+
+    Can be used with any nodes that operate with ``ast.Name`` or ``ast.Tuple``
+    as targets for the assignment.
+
+    Can be used with nodes like ``ast.Assign``, ``ast.Tuple``, ``ast.For``,
+    ``ast.With``, etc.
+    """
     names: List[str] = []
     naive_attempt = extract_name(node)
 
@@ -61,7 +88,19 @@ def extract_name(node: ast.AST) -> Optional[str]:
     """
     Utility to extract names for several types of nodes.
 
-    Should not be used direclty, use safer :py:`~get_assign_names` function.
+    Is used to get name from node in case it is ``ast.Name``.
+
+    Should not be used direclty with assigns,
+    use safer :py:`~get_assign_names` function.
+
+    Example:
+
+    >>> import ast
+    >>> tree = ast.parse('a')
+    >>> node = tree.body[0].value
+    >>> extract_name(node)
+    'a'
+
     """
     if isinstance(node, ast.Starred):
         node = node.value

wemake_python_styleguide/transformations/ast/enhancements.py

@@ -4,6 +4,7 @@
 from typing import Optional, Tuple, Type
 
 from wemake_python_styleguide.compat.aliases import FunctionNodes
+from wemake_python_styleguide.logic.nodes import get_parent
 from wemake_python_styleguide.types import ContextNodes
 
 
@@ -86,7 +87,7 @@ def _find_context(
     It happened because of the bug #520
     See: https://github.com/wemake-services/wemake-python-styleguide/issues/520
     """
-    parent = getattr(node, 'wps_parent', None)
+    parent = get_parent(node)
     if parent is None:
         return None
     elif isinstance(parent, contexts):

wemake_python_styleguide/visitors/ast/builtins.py

@@ -9,6 +9,7 @@
 
 from wemake_python_styleguide import constants
 from wemake_python_styleguide.compat.aliases import FunctionNodes
+from wemake_python_styleguide.logic.naming.name_nodes import extract_name
 from wemake_python_styleguide.logic.nodes import get_parent
 from wemake_python_styleguide.logic.operators import (
     count_unary_operator,
@@ -34,12 +35,11 @@
     FormattedStringViolation,
     UselessOperatorsViolation,
 )
-from wemake_python_styleguide.visitors.base import BaseNodeVisitor
-from wemake_python_styleguide.visitors.decorators import alias
+from wemake_python_styleguide.visitors import base, decorators
 
 
 @final
-class WrongStringVisitor(BaseNodeVisitor):
+class WrongStringVisitor(base.BaseNodeVisitor):
     """Restricts several string usages."""
 
     def __init__(self, *args, **kwargs) -> None:
@@ -93,7 +93,7 @@ def _post_visit(self) -> None:
 
 
 @final
-class MagicNumberVisitor(BaseNodeVisitor):
+class MagicNumberVisitor(base.BaseNodeVisitor):
     """Checks magic numbers used in the code."""
 
     _allowed_parents: ClassVar[AnyNodes] = (
@@ -137,7 +137,7 @@ def _check_is_magic(self, node: ast.Num) -> None:
 
 
 @final
-class UselessOperatorsVisitor(BaseNodeVisitor):
+class UselessOperatorsVisitor(base.BaseNodeVisitor):
     """Checks operators used in the code."""
 
     _limits: ClassVar[Mapping[AnyUnaryOp, int]] = {
@@ -167,15 +167,15 @@ def _check_operator_count(self, node: ast.Num) -> None:
 
 
 @final
-@alias('visit_any_for', (
+@decorators.alias('visit_any_for', (
     'visit_For',
     'visit_AsyncFor',
 ))
-@alias('visit_any_with', (
+@decorators.alias('visit_any_with', (
     'visit_With',
     'visit_AsyncWith',
 ))
-class WrongAssignmentVisitor(BaseNodeVisitor):
+class WrongAssignmentVisitor(base.BaseNodeVisitor):
     """Visits all assign nodes."""
 
     def visit_any_with(self, node: AnyWith) -> None:
@@ -241,14 +241,13 @@ def _check_unpacking_targets(
         targets: Iterable[ast.AST],
     ) -> None:
         for target in targets:
-            if isinstance(target, ast.Starred):
-                target = target.value  # noqa: WPS440
-            if not isinstance(target, ast.Name):
+            target_name = extract_name(target)
+            if target_name is None:  # it means, that non name node was used
                 self.add_violation(WrongUnpackingViolation(node))
 
 
 @final
-class WrongCollectionVisitor(BaseNodeVisitor):
+class WrongCollectionVisitor(base.BaseNodeVisitor):
     """Ensures that collection definitions are correct."""
 
     _elements_in_sets: ClassVar[AnyNodes] = (

wemake_python_styleguide/visitors/ast/complexity/function.py

@@ -85,9 +85,7 @@ def _update_variables(
 
     def _check_sub_node(self, node: AnyFunctionDef, sub_node) -> None:
         is_variable = isinstance(sub_node, ast.Name)
-        context = getattr(sub_node, 'ctx', None)
-
-        if is_variable and isinstance(context, ast.Store):
+        if is_variable and isinstance(sub_node.ctx, ast.Store):
             self._update_variables(node, sub_node)
         elif isinstance(sub_node, ast.Return):
             self.returns[node] += 1

wemake_python_styleguide/visitors/ast/exceptions.py

@@ -91,7 +91,7 @@ def _check_if_needs_except(self, node: ast.Try) -> None:
             self.add_violation(UselessFinallyViolation(node))
 
     def _check_exception_type(self, node: ast.ExceptHandler) -> None:
-        exception_name = getattr(node, 'type', None)
+        exception_name = node.type
         if exception_name is None:
             return
 

wemake_python_styleguide/visitors/ast/naming.py

@@ -298,10 +298,7 @@ def visit_any_assign(self, node: AnyAssign) -> None:
             ReassigningVariableToItselfViolation
 
         """
-        names = list(itertools.chain.from_iterable((
-            name_nodes.get_variables_from_node(target)
-            for target in get_assign_targets(node)
-        )))
+        names = list(name_nodes.flat_variable_names([node]))
 
         self._check_reassignment(node, names)
         self._check_unique_assignment(node, names)