Changeset 1934 for trunk/packages/invirt-base/python/invirt/common.py

Timestamp:

Dec 28, 2008, 7:20:07 PM (16 years ago)

Author:

price

Message:

invirt.common: give clearer error message on missing config variable

File:

• trunk/packages/invirt-base/python/invirt/common.py (modified) (2 diffs)

trunk/packages/invirt-base/python/invirt/common.py

@@ -5 +5 @@
 import contextlib as clib
 
+class InvirtConfigError(AttributeError):
+    pass
+
 class struct(object):
     'A simple namespace object.'
-    def __init__(self, d = {}, **kwargs):
-        'd is the dictionary to update my __dict__ with.'
+    def __init__(self, d = {}, __prefix = None, **kwargs):
+        'd is the dictionary or the items-iterable to update my __dict__ with.'
         self.__dict__.update(d)
         self.__dict__.update(kwargs)
+        self.__prefix = __prefix
+    def __getattr__(self, key):
+        # XX ideally these would point a frame higher on the stack.
+        prefix = self.__prefix
+        if prefix is not None:
+            raise InvirtConfigError('missing configuration variable %s%s'
+                                    % (prefix, key))
+        else:
+            raise AttributeError("anonymous struct has no member '%s'"
+                                 % (key,))
 
-def dicts2struct(x):
+def dicts2struct(x, prefix = None):
     """
     Given a tree of lists/dicts, perform a deep traversal to transform all the
     dicts to structs.
     """
+    if prefix is not None:
+        def newprefix(k): return prefix + str(k) + '.'
+    else:
+        def newprefix(k): return prefix
     if type(x) == dict:
-        return struct((k, dicts2struct(v)) for k,v in x.iteritems())
+        return struct(((k, dicts2struct(v, newprefix(k)))
+                       for k,v in x.iteritems()),
+                      prefix)
     elif type(x) == list:
-        return [dicts2struct(v) for v in x]
+        return [dicts2struct(v, newprefix(i)) for i, v in enumerate(x)]
     else:
         return x
@@ -68 +87 @@
                 'list': [ 'atom', {'key': 'value'} ]
                 }
-        structs = dicts2struct(dicts)
+        structs = dicts2struct(dicts, '')
         self.assertEqual(structs.atom,        dicts['atom'])
         self.assertEqual(structs.dict.atom,   dicts['dict']['atom'])