8th day of python challenges 111-117

venv/lib/python3.6/site-packages/pylint/extensions/overlapping_exceptions.py

@@ -0,0 +1,90 @@
+# -*- coding: utf-8 -*-
+
+# 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
+
+"""Looks for overlapping exceptions."""
+
+import astroid
+
+from pylint import interfaces
+from pylint import checkers
+from pylint.checkers import utils
+
+from pylint.checkers.exceptions import _annotated_unpack_infer
+
+
+class OverlappingExceptionsChecker(checkers.BaseChecker):
+    """Checks for two or more exceptions in the same exception handler
+    clause that are identical or parts of the same inheritance hierarchy
+    (i.e. overlapping)."""
+
+    __implements__ = interfaces.IAstroidChecker
+
+    name = "overlap-except"
+    msgs = {
+        "W0714": (
+            "Overlapping exceptions (%s)",
+            "overlapping-except",
+            "Used when exceptions in handler overlap or are identical",
+        )
+    }
+    priority = -2
+    options = ()
+
+    @utils.check_messages("overlapping-except")
+    def visit_tryexcept(self, node):
+        """check for empty except"""
+        for handler in node.handlers:
+            if handler.type is None:
+                continue
+            if isinstance(handler.type, astroid.BoolOp):
+                continue
+            try:
+                excs = list(_annotated_unpack_infer(handler.type))
+            except astroid.InferenceError:
+                continue
+
+            handled_in_clause = []
+            for part, exc in excs:
+                if exc is astroid.Uninferable:
+                    continue
+                if isinstance(exc, astroid.Instance) and utils.inherit_from_std_ex(exc):
+                    # pylint: disable=protected-access
+                    exc = exc._proxied
+
+                if not isinstance(exc, astroid.ClassDef):
+                    continue
+
+                exc_ancestors = [
+                    anc for anc in exc.ancestors() if isinstance(anc, astroid.ClassDef)
+                ]
+
+                for prev_part, prev_exc in handled_in_clause:
+                    prev_exc_ancestors = [
+                        anc
+                        for anc in prev_exc.ancestors()
+                        if isinstance(anc, astroid.ClassDef)
+                    ]
+                    if exc == prev_exc:
+                        self.add_message(
+                            "overlapping-except",
+                            node=handler.type,
+                            args="%s and %s are the same"
+                            % (prev_part.as_string(), part.as_string()),
+                        )
+                    elif prev_exc in exc_ancestors or exc in prev_exc_ancestors:
+                        ancestor = part if exc in prev_exc_ancestors else prev_part
+                        descendant = part if prev_exc in exc_ancestors else prev_part
+                        self.add_message(
+                            "overlapping-except",
+                            node=handler.type,
+                            args="%s is an ancestor class of %s"
+                            % (ancestor.as_string(), descendant.as_string()),
+                        )
+                handled_in_clause += [(part, exc)]
+
+
+def register(linter):
+    """Required method to auto register this checker."""
+    linter.register_checker(OverlappingExceptionsChecker(linter))