Example of refactoring using rope library.

tools/telemetry/third_party/rope/rope/contrib/finderrors.py

Index: tools/telemetry/third_party/rope/rope/contrib/finderrors.py
diff --git a/tools/telemetry/third_party/rope/rope/contrib/finderrors.py b/tools/telemetry/third_party/rope/rope/contrib/finderrors.py
new file mode 100644
index 0000000000000000000000000000000000000000..9ee7dd15f97a738ec757c17aaf5637aade9bcf4a
--- /dev/null
+++ b/tools/telemetry/third_party/rope/rope/contrib/finderrors.py
@@ -0,0 +1,91 @@
+"""Finding bad name and attribute accesses
+
+`find_errors` function can be used to find possible bad name and
+attribute accesses.  As an example::
+
+  errors = find_errors(project, project.get_resource('mod.py'))
+  for error in errors:
+      print '%s: %s' % (error.lineno, error.error)
+
+prints possible errors for ``mod.py`` file.
+
+TODO:
+
+* use task handles
+* reporting names at most once
+* attributes of extension modules that don't appear in
+  extension_modules project config can be ignored
+* not calling `PyScope.get_inner_scope_for_line()` if it is a
+  bottleneck; needs profiling
+* not reporting occurrences where rope cannot infer the object
+* rope saves multiple objects for some of the names in its objectdb
+  use all of them not to give false positives
+* ... ;-)
+
+"""
+from rope.base import ast, evaluate, pyobjects
+
+
+def find_errors(project, resource):
+    """Find possible bad name and attribute accesses
+
+    It returns a list of `Error`\s.
+    """
+    pymodule = project.get_pymodule(resource)
+    finder = _BadAccessFinder(pymodule)
+    ast.walk(pymodule.get_ast(), finder)
+    return finder.errors
+
+
+class _BadAccessFinder(object):
+
+    def __init__(self, pymodule):
+        self.pymodule = pymodule
+        self.scope = pymodule.get_scope()
+        self.errors = []
+
+    def _Name(self, node):
+        if isinstance(node.ctx, (ast.Store, ast.Param)):
+            return
+        scope = self.scope.get_inner_scope_for_line(node.lineno)
+        pyname = scope.lookup(node.id)
+        if pyname is None:
+            self._add_error(node, 'Unresolved variable')
+        elif self._is_defined_after(scope, pyname, node.lineno):
+            self._add_error(node, 'Defined later')
+
+    def _Attribute(self, node):
+        if not isinstance(node.ctx, ast.Store):
+            scope = self.scope.get_inner_scope_for_line(node.lineno)
+            pyname = evaluate.eval_node(scope, node.value)
+            if pyname is not None and \
+               pyname.get_object() != pyobjects.get_unknown():
+                if node.attr not in pyname.get_object():
+                    self._add_error(node, 'Unresolved attribute')
+        ast.walk(node.value, self)
+
+    def _add_error(self, node, msg):
+        if isinstance(node, ast.Attribute):
+            name = node.attr
+        else:
+            name = node.id
+        if name != 'None':
+            error = Error(node.lineno, msg + ' ' + name)
+            self.errors.append(error)
+
+    def _is_defined_after(self, scope, pyname, lineno):
+        location = pyname.get_definition_location()
+        if location is not None and location[1] is not None:
+            if location[0] == self.pymodule and \
+               lineno <= location[1] <= scope.get_end():
+                return True
+
+
+class Error(object):
+
+    def __init__(self, lineno, error):
+        self.lineno = lineno
+        self.error = error
+
+    def __str__(self):
+        return '%s: %s' % (self.lineno, self.error)