--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lookup_list.py	Wed Mar 26 21:05:14 2008 -0400
@@ -0,0 +1,69 @@
+
+class LookupList(object):
+    """
+    A LookupList is a sequence whose elements can be named (and unlike
+    a dictionary the order of the elements depends not on their key but
+    on the order given by the user through construction) so that
+    following syntactic constructions work as one would expect:
+       example = Example(['x','y','z'],[1,2,3])
+       example.x = [1, 2, 3] # set or change a field
+       x, y, z = example
+       x = example[0]
+       x = example["x"]
+       print example.keys() # returns ['x','y','z']
+       print example.values() # returns [[1,2,3],2,3]
+    """
+    def __init__(self,names=[],values=[]):
+        assert len(values)==len(names)
+        self.__dict__['_values']=values
+        self.__dict__['_name2index']={}
+        self.__dict__['_names']=names
+        for i in xrange(len(values)):
+            self._name2index[names[i]]=i
+
+    def keys(self):
+        return self._names
+
+    def values(self):
+        return self._values
+
+    def items(self):
+        return zip(self._names,self._values)
+    
+    def __getitem__(self,key):
+        """
+        The key in example[key] can either be an integer to index the fields
+        or the name of the field.
+        """
+        if isinstance(key,int):
+            return self._values[key]
+        else: # if not an int, key must be a name
+            return self._values[self._name2index[key]]
+    
+    def __setitem__(self,key,value):
+        if isinstance(key,int):
+            self._values[key]=value
+        else: # if not an int, key must be a name
+            if key in self._name2index:
+                self._values[self._name2index[key]]=value
+            else:
+                self._name2index[key]=len(self)
+                self._values.append(value)
+                self._names.append(key)
+
+    def __getattr__(self,name):
+        return self._values[self._name2index[name]]
+
+    def __setattr__(self,name,value):
+        if name in self._name2index:
+            self._values[self._name2index[name]]=value
+        else:
+            self._name2index[name]=len(self)
+            self._values.append(value)
+            self._names.append(name)
+
+    def __len__(self):
+        return len(self._values)
+
+    def __repr__(self):
+        return "{%s}" % ", ".join([str(k) + "=" + repr(v) for k,v in self.items()])