Introduced DeprecatedMixin

ChangeLog

@@ -1,6 +1,10 @@
 ------------------
 Pylint's ChangeLog
 ------------------
+* Introduce DeprecationMixin for reusable deprecation checks.
+
+  Closes #4049
+
 * Bug fix for empty-comment message line number.
 
   Closes #4009

pylint/checkers/__init__.py

@@ -44,6 +44,7 @@
 """
 
 from pylint.checkers.base_checker import BaseChecker, BaseTokenChecker
+from pylint.checkers.deprecated import DeprecatedMixin
 from pylint.checkers.mapreduce_checker import MapReduceMixin
 from pylint.utils import register_plugins
 

pylint/checkers/deprecated.py

@@ -0,0 +1,36 @@
+# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+# For details: https://github.com/PyCQA/pylint/blob/master/COPYING
+
+"""Checker mixin for deprecated functionality."""
+
+import abc
+
+import astroid
+
+
+class DeprecatedMixin(metaclass=abc.ABCMeta):
+    @abc.abstractmethod
+    def deprecated_methods(self):
+        """Returns Iterator of deprecated methods."""
+
+    def check_deprecated_method(self, node, inferred):
+
+        if isinstance(node.func, astroid.Attribute):
+            func_name = node.func.attrname
+        elif isinstance(node.func, astroid.Name):
+            func_name = node.func.name
+        else:
+            # Not interested in other nodes.
+            return
+
+        # Reject nodes which aren't of interest to us.
+        acceptable_nodes = (
+            astroid.BoundMethod,
+            astroid.UnboundMethod,
+            astroid.FunctionDef,
+        )
+        if not isinstance(inferred, acceptable_nodes):
+            return
+        qname = inferred.qname()
+        if any(name in self.deprecated_methods() for name in (qname, func_name)):
+            self.add_message("deprecated-method", node=node, args=(func_name,))

pylint/checkers/stdlib.py

@@ -36,7 +36,7 @@
 from astroid.bases import Instance
 from astroid.node_classes import Const
 
-from pylint.checkers import BaseChecker, utils
+from pylint.checkers import BaseChecker, DeprecatedMixin, utils
 from pylint.interfaces import IAstroidChecker
 
 OPEN_FILES = {"open", "file"}
@@ -80,7 +80,7 @@ def _check_mode_str(mode):
     return True
 
 
-class StdlibChecker(BaseChecker):
+class StdlibChecker(BaseChecker, DeprecatedMixin):
     __implements__ = (IAstroidChecker,)
     name = "stdlib"
 
@@ -336,7 +336,7 @@ def visit_call(self, node):
                         self._check_env_function(node, inferred)
                     elif name == SUBPROCESS_RUN:
                         self._check_for_check_kw_in_run(node)
-                self._check_deprecated_method(node, inferred)
+                self.check_deprecated_method(node, inferred)
         except astroid.InferenceError:
             return
 
@@ -358,37 +358,6 @@ def visit_boolop(self, node):
         for value in node.values:
             self._check_datetime(value)
 
-    def _check_deprecated_method(self, node, inferred):
-        py_vers = sys.version_info[0]
-
-        if isinstance(node.func, astroid.Attribute):
-            func_name = node.func.attrname
-        elif isinstance(node.func, astroid.Name):
-            func_name = node.func.name
-        else:
-            # Not interested in other nodes.
-            return
-
-        # Reject nodes which aren't of interest to us.
-        acceptable_nodes = (
-            astroid.BoundMethod,
-            astroid.UnboundMethod,
-            astroid.FunctionDef,
-        )
-        if not isinstance(inferred, acceptable_nodes):
-            return
-
-        qname = inferred.qname()
-        if any(name in self.deprecated[0] for name in (qname, func_name)):
-            self.add_message("deprecated-method", node=node, args=(func_name,))
-        else:
-            for since_vers, func_list in self.deprecated[py_vers].items():
-                if since_vers <= sys.version_info and any(
-                    name in func_list for name in (qname, func_name)
-                ):
-                    self.add_message("deprecated-method", node=node, args=(func_name,))
-                    break
-
     def _check_redundant_assert(self, node, infer):
         if (
             isinstance(infer, astroid.BoundMethod)
@@ -481,6 +450,15 @@ def _check_invalid_envvar_value(self, node, infer, message, call_arg, allow_none
         else:
             self.add_message(message, node=node, args=(name, call_arg.pytype()))
 
+    def deprecated_methods(self):
+        py_vers = sys.version_info[0]
+        deprecated_methods = set()
+        deprecated_methods.update(self.deprecated[0])
+        for since_vers, func_list in self.deprecated[py_vers].items():
+            if since_vers <= sys.version_info:
+                deprecated_methods.update(func_list)
+        return deprecated_methods
+
 
 def register(linter):
     """required method to auto register this checker """