Changed the way how parameters are being built

The old way consisted in having the parameter names, their
defaults and their annotations separated in different components
of the Arguments node. We introduced a new Param node, which holds
the name of a parameter, its default value and its annotation.
If any of the last two values are missing, then that slot will be
filled with a new node kind, Empty, which is used for specifying the
lack of something (None could have been used instead, but that means having
non-AST nodes in the Arguments node).
We're also having support for positional only arguments, for the moment
only in raw_building.

Close #215

1 files changed, 4 insertions, 3 deletions

diff --git a/astroid/protocols.py b/astroid/protocols.py
index eada9764..7fdc6e29 100644
--- a/astroid/protocols.py
+++ b/astroid/protocols.py
@@ -304,6 +304,7 @@ def mulass_assigned_stmts(self, nodes, node=None, context=None, assign_path=None
 
 @assigned_stmts.register(treeabc.AssignName)
 @assigned_stmts.register(treeabc.AssignAttr)
+@assigned_stmts.register(treeabc.Parameter)
 def assend_assigned_stmts(self, nodes, node=None, context=None, assign_path=None):
     return self.parent.assigned_stmts(self, context=context)
 
@@ -311,7 +312,7 @@ def assend_assigned_stmts(self, nodes, node=None, context=None, assign_path=None
 def _arguments_infer_argname(self, name, context, nodes):
     # arguments information may be missing, in which case we can't do anything
     # more
-    if not (self.args or self.vararg or self.kwarg):
+    if not self.args and (not self.vararg and not self.kwarg):
         yield util.Uninferable
         return
     # first argument of instance/class method
@@ -336,10 +337,10 @@ def _arguments_infer_argname(self, name, context, nodes):
         return
 
     # TODO: just provide the type here, no need to have an empty Dict.
-    if name == self.vararg:
+    if self.vararg and name == self.vararg.name:
         yield nodes.Tuple(parent=self)
         return
-    if name == self.kwarg:
+    if self.kwarg and name == self.kwarg.name:
         yield nodes.Dict(parent=self)
         return
     # if there is a default value, yield it. And then yield Uninferable to reflect