- Clearer and better code for handling relation comparisons

git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@252 014f5005-505e-4b48-8d0a-63407b615a7c

CHANGELOG

@@ -2,6 +2,7 @@
 - Removed encoding from .desktop file (was deprecated)
 - Added manpage for relational-cli
 - Internally uses set instead of lists to describe relation's content
+- Tuples are internally mapped on tuples and no longer on lists
 - Discards the old and not so functional tlb format
 - Rename will mark the resulting relation as readonly and subsequent updates, insert or deletes will actually copy the content
 

relational/relation.py

@@ -381,16 +381,13 @@ class relation (object):
     def __eq__(self,other):
         '''Returns true if the relations are the same, ignoring order of items.
         This operation is rather heavy, since it requires sorting and comparing.'''
-        other=self._rearrange_(other) #Rearranges attributes' order so can compare tuples directly
         if (self.__class__!=other.__class__)or(self.header!=other.header):
             return False #Both parameters must be a relation
+
+        if set(self.header.attributes)!=set(other.header.attributes):
+            return False
         
-        #Comparing header
+        other=self._rearrange_(other) #Rearranges attributes' order so can compare tuples directly
-        if len(self.header.attributes) != len(other.header.attributes):
-            return False #Not the same number of attributes -> not equals
-        for i in self.header.attributes:
-            if i not in other.header.attributes:
-                return False #Non shared attribute
         
         #comparing content
         return self.content==other.content