Index: Lib/decimal.py
===================================================================
--- Lib/decimal.py	(revision 82414)
+++ Lib/decimal.py	(working copy)
@@ -3810,21 +3810,41 @@
                  Emin=None, Emax=None,
                  capitals=None, clamp=None,
                  _ignored_flags=None):
+        # Set defaults; for everything except flags and _ignored_flags,
+        # inherit from DefaultContext.
+        if prec is None:
+            prec = DefaultContext.prec
+        if rounding is None:
+            rounding = DefaultContext.rounding
+        if traps is None:
+            traps = dict(DefaultContext.traps)
+        elif not isinstance(traps, dict):
+            traps = {s: int(s in traps) for s in _signals}
         if flags is None:
-            flags = []
+            flags = {s: 0 for s in _signals}
+        elif not isinstance(flags, dict):
+            flags = {s: int(s in flags) for s in _signals}
+        if Emin is None:
+            Emin = DefaultContext.Emin
+        if Emax is None:
+            Emax = DefaultContext.Emax
+        if capitals is None:
+            capitals = DefaultContext.capitals
+        if clamp is None:
+            clamp = DefaultContext.clamp
         if _ignored_flags is None:
             _ignored_flags = []
-        if not isinstance(flags, dict):
-            flags = dict([(s, int(s in flags)) for s in _signals])
-        if traps is not None and not isinstance(traps, dict):
-            traps = dict([(s, int(s in traps)) for s in _signals])
-        for name, val in locals().items():
-            if val is None:
-                setattr(self, name, _copy.copy(getattr(DefaultContext, name)))
-            else:
-                setattr(self, name, val)
-        del self.self
 
+        self.prec = prec
+        self.rounding = rounding
+        self.traps = traps
+        self.flags = flags
+        self.Emin = Emin
+        self.Emax = Emax
+        self.capitals = capitals
+        self.clamp = clamp
+        self._ignored_flags = _ignored_flags
+
     def __repr__(self):
         """Show the current context."""
         s = []