Add no-dict-subscript checker

Author: pmiddend

doc/whatsnew/2/2.15/index.rst

@@ -15,14 +15,17 @@ Summary -- Release highlights
 New checkers
 ============
 
-
 Removed checkers
 ================
 
 
 Extensions
 ==========
 
+* ``NoDictSubscriptChecker``
+
+    * Added optional extension ``no-dict-subscript`` to emit messages when the ``[]`` operator is used
+      to access a dictionary value.
 
 False positives fixed
 =====================

pylint/checkers/misc.py

@@ -10,9 +10,9 @@
 import tokenize
 from typing import TYPE_CHECKING
 
-from astroid import Assign, Dict, nodes
+from astroid import nodes
 
-from pylint.checkers import BaseChecker, BaseRawFileChecker, BaseTokenChecker, utils
+from pylint.checkers import BaseRawFileChecker, BaseTokenChecker
 from pylint.typing import ManagedMessage
 from pylint.utils.pragma_parser import OPTION_PO, PragmaParserError, parse_pragma
 
@@ -176,24 +176,6 @@ def process_tokens(self, tokens: list[tokenize.TokenInfo]) -> None:
                 )
 
 
-class NoDictDirectAccessChecker(BaseChecker):
-    name = "no-dict-direct-access"
-    msgs = {
-        "W0001": (
-            "Uses dict operator []",
-            "dict-direct-access",
-            "Used to warn when subscripting a dictionary instead of using the get() function",
-        ),
-    }
-
-    def visit_subscript(self, node: nodes.Subscript) -> None:
-        if isinstance(utils.safe_infer(node.value), Dict) and not isinstance(
-            node.parent, Assign
-        ):
-            self.add_message("dict-direct-access", node=node)
-
-
 def register(linter: PyLinter) -> None:
     linter.register_checker(EncodingChecker(linter))
     linter.register_checker(ByIdManagedMessagesChecker(linter))
-    linter.register_checker(NoDictDirectAccessChecker(linter))

pylint/extensions/dictionary_subscript.py

@@ -0,0 +1,30 @@
+# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+# For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
+# Copyright (c) https://github.com/PyCQA/pylint/blob/main/CONTRIBUTORS.txt
+
+"""Check for dictionary read-access via subscript"""
+
+from astroid import nodes, Dict, Assign
+
+from pylint.checkers import BaseChecker, utils
+from pylint.lint import PyLinter
+
+
+class NoDictSubscriptChecker(BaseChecker):
+    name = "no-dict-subscript"
+    msgs = {
+        "W0001": (
+            "Uses dict operator []",
+            "dict-subscript",
+            "Used to warn when subscripting a dictionary instead of using the get() function",
+        ),
+    }
+
+    def visit_subscript(self, node: nodes.Subscript) -> None:
+        if isinstance(utils.safe_infer(node.value), Dict) and not isinstance(
+                node.parent, Assign
+        ):
+            self.add_message("dict-subscript", node=node)
+
+def register(linter: PyLinter) -> None:
+    linter.register_checker(NoDictSubscriptChecker(linter))