# HG changeset patch
# User paulb@localhost.localdomain
# Date 1182119746 -7200
# Node ID 73351400ca6dff58043fa84a7081011275c109b8
# Parent  ff6cb84e2fc7d8d33b82ba7288be429393a7c6ce
Added a method which attempts to return distinct instances from those stored for
a particular class.
Improved the docstrings.


diff -r ff6cb84e2fc7 -r 73351400ca6d simplify/simplified/data.py
--- a/simplify/simplified/data.py	Sun Jun 17 22:05:04 2007 +0200
+++ b/simplify/simplified/data.py	Mon Jun 18 00:35:46 2007 +0200
@@ -28,7 +28,10 @@
 
 class _Class(Structure, WithName):
 
-    "A Python class."
+    """
+    The basis of a Python class. Classes with specific instantiation behaviour
+    should inherit from this class.
+    """
 
     def __init__(self, *args, **kw):
         Structure.__init__(self, *args, **kw)
@@ -37,6 +40,8 @@
     def full_name(self):
         return "class %s" % self._full_name
 
+    # Utility methods.
+
     def get_instance_attribute_names(self):
 
         "Return all attribute names used by the instances of this class."
@@ -63,9 +68,32 @@
         names.sort()
         return d, names
 
+    def get_distinct_instances(self):
+
+        """
+        Return a list of instances whose instance attribute types are distinct.
+        """
+
+        instances = []
+        names_found = []
+
+        # Rather than use the instances directly, get them in name order in
+        # order to favour those earlier according to the sorting.
+
+        names_to_instances, instance_names = self.get_names_to_instances()
+
+        for instance_name in instance_names:
+            instance = names_to_instances[instance_name]
+            names = instance.namespace.names
+            if not names in names_found:
+                instances.append(instance)
+                names_found.append(names)
+                
+        return instances
+
 class SingleInstanceClass(_Class):
 
-    "A Python class."
+    "A Python class producing only one instance."
 
     def __init__(self, *args, **kw):
         _Class.__init__(self, *args, **kw)
@@ -90,7 +118,7 @@
 
 class MultipleInstanceClass(_Class):
 
-    "A Python class."
+    "A Python class producing many instances."
 
     def __init__(self, *args, **kw):
         _Class.__init__(self, *args, **kw)