- Added an improved repr() to TypeEngine objects

that will only display constructor args which
are positional or kwargs that deviate
from the default.  [ticket:2209]

3 files changed, 30 insertions, 6 deletions

diff --git a/lib/sqlalchemy/types.py b/lib/sqlalchemy/types.py
index e8d0b6f22..c7781a76f 100644
--- a/lib/sqlalchemy/types.py
+++ b/lib/sqlalchemy/types.py
@@ -263,11 +263,7 @@ class TypeEngine(AbstractType):
                     "constructor %s is deprecated" % self.__class__)
 
     def __repr__(self):
-        return "%s(%s)" % (
-            self.__class__.__name__,
-            ", ".join("%s=%r" % (k, getattr(self, k, None))
-                      for k in inspect.getargspec(self.__init__)[0][1:]))
-
+        return util.generic_repr(self)
 
 class UserDefinedType(TypeEngine):
     """Base for user defined types.
diff --git a/lib/sqlalchemy/util/__init__.py b/lib/sqlalchemy/util/__init__.py
index 827fce088..4b7a43752 100644
--- a/lib/sqlalchemy/util/__init__.py
+++ b/lib/sqlalchemy/util/__init__.py
@@ -26,7 +26,8 @@ from langhelpers import iterate_attributes, class_hierarchy, \
     monkeypatch_proxied_specials, asbool, bool_or_str, coerce_kw_type,\
     duck_type_collection, assert_arg_type, symbol, dictlike_iteritems,\
     classproperty, set_creation_order, warn_exception, warn, NoneType,\
-    constructor_copy, methods_equivalent, chop_traceback, asint
+    constructor_copy, methods_equivalent, chop_traceback, asint,\
+    generic_repr
 
 from deprecations import warn_deprecated, warn_pending_deprecation, \
     deprecated, pending_deprecation
diff --git a/lib/sqlalchemy/util/langhelpers.py b/lib/sqlalchemy/util/langhelpers.py
index e9213845b..c3a358220 100644
--- a/lib/sqlalchemy/util/langhelpers.py
+++ b/lib/sqlalchemy/util/langhelpers.py
@@ -215,6 +215,33 @@ def unbound_method_to_callable(func_or_cls):
     else:
         return func_or_cls
 
+def generic_repr(obj):
+    """Produce a __repr__() based on direct association of the __init__()
+    specification vs. same-named attributes present.
+    
+    """
+    def genargs():
+        try:
+            (args, vargs, vkw, defaults) = inspect.getargspec(obj.__init__)
+        except TypeError:
+            return
+
+        default_len = defaults and len(defaults) or 0
+
+        if not default_len:
+            for arg in args[1:]:
+                yield repr(getattr(obj, arg, None))
+            if vargs is not None and hasattr(obj, vargs):
+                yield ', '.join(repr(val) for val in getattr(obj, vargs))
+        else:
+            for arg in args[1:-default_len]:
+                yield repr(getattr(obj, arg, None))
+            for (arg, defval) in zip(args[-default_len:], defaults):
+                val = getattr(obj, arg, None)
+                if val != defval:
+                    yield '%s=%r' % (arg, val)
+    return "%s(%s)" % (obj.__class__.__name__, ", ".join(genargs()))
+
 class portable_instancemethod(object):
     """Turn an instancemethod into a (parent, name) pair
     to produce a serializable callable.