This bookmark adds structured exceptions to astroid.

Major changes:
* AstroidError has an __init__ that accepts arbitrary keyword-only
  arguments for adding information to exceptions, and a __str__ that
  lazily uses exception attributes to generate a message.  The first
  positional argument to an exception is assigned to .message.  The new
  API should be fully backwards compatible in general.
* Some exceptions are combined or renamed; the old names are still
  available.
* The OperationErrors used by pylint are now BadOperationMessages and
  located in util.py.
* The AstroidBuildingException in _data_build stores the SyntaxError
  in its .error attribute rather than args[0].
* Many places where exceptions are raised have new, hopefully more
  useful error messages.

The only major issue remaining is how to propagate information into decorators.

1 files changed, 9 insertions, 8 deletions

diff --git a/astroid/node_classes.py b/astroid/node_classes.py
index 7da41f5..5a92210 100644
--- a/astroid/node_classes.py
+++ b/astroid/node_classes.py
@@ -412,7 +412,8 @@ class NodeNG(object):
     def _infer(self, context=None):
         """we don't know how to resolve a statement by default"""
         # this method is overridden by most concrete classes
-        raise exceptions.InferenceError(self.__class__.__name__)
+        raise exceptions.InferenceError('No inference function for {node!r}.',
+                                        node=self, context=context)
 
     def inferred(self):
         '''return list of inferred values for a more simple inference usage'''
@@ -894,7 +895,7 @@ class Arguments(mixins.AssignTypeMixin, NodeNG):
         i = _find_arg(argname, self.kwonlyargs)[0]
         if i is not None and self.kw_defaults[i] is not None:
             return self.kw_defaults[i]
-        raise exceptions.NoDefault()
+        raise exceptions.NoDefault(func=self.parent, name=argname)
 
     def is_argument(self, name):
         """return True if the name is defined in arguments"""
@@ -1011,13 +1012,13 @@ class AugAssign(mixins.AssignTypeMixin, Statement):
     def type_errors(self, context=None):
         """Return a list of TypeErrors which can occur during inference.
 
-        Each TypeError is represented by a :class:`BinaryOperationError`,
+        Each TypeError is represented by a :class:`BadBinaryOperationMessage`,
         which holds the original exception.
         """
         try:
             results = self._infer_augassign(context=context)
             return [result for result in results
-                    if isinstance(result, exceptions.BinaryOperationError)]
+                    if isinstance(result, util.BadBinaryOperationMessage)]
         except exceptions.InferenceError:
             return []
 
@@ -1053,13 +1054,13 @@ class BinOp(NodeNG):
     def type_errors(self, context=None):
         """Return a list of TypeErrors which can occur during inference.
 
-        Each TypeError is represented by a :class:`BinaryOperationError`,
+        Each TypeError is represented by a :class:`BadBinaryOperationMessage`,
         which holds the original exception.
         """
         try:
             results = self._infer_binop(context=context)
             return [result for result in results
-                    if isinstance(result, exceptions.BinaryOperationError)]
+                    if isinstance(result, util.BadBinaryOperationMessage)]
         except exceptions.InferenceError:
             return []
 
@@ -1745,13 +1746,13 @@ class UnaryOp(NodeNG):
     def type_errors(self, context=None):
         """Return a list of TypeErrors which can occur during inference.
 
-        Each TypeError is represented by a :class:`UnaryOperationError`,
+        Each TypeError is represented by a :class:`BadUnaryOperationMessage`,
         which holds the original exception.
         """
         try:
             results = self._infer_unaryop(context=context)
             return [result for result in results
-                    if isinstance(result, exceptions.UnaryOperationError)]
+                    if isinstance(result, util.BadUnaryOperationMessage)]
         except exceptions.InferenceError:
             return []