- Set hash method for the classes

git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@265 014f5005-505e-4b48-8d0a-63407b615a7c

CHANGELOG

@@ -10,6 +10,7 @@
 - Fixed optimization involving selection and parenthesis in the expression (Rev 260)
 - Fixed futile_union_intersection_subtraction optimization that didn't work when selection operator was in the left subtree (Rev 261)
 - Module parallel does something, can execute queries in parallel
+- Set hash method for the classes
 
 0.11
 - Font is set only on windows (Rev 206)

relational/parser.py

@@ -51,6 +51,7 @@ class node (object):
     
     This class is used to convert an expression into python code.'''
     kind=None
+    __hash__=None
     
     def __init__(self,expression=None):
         '''Generates the tree from the tokenized expression
@@ -186,6 +187,7 @@ class node (object):
         if self.kind==BINARY:
             return self.left==other.left and self.right==other.right
         return True
+        
     def __str__(self):
         if (self.kind==RELATION):
             return self.name

relational/relation.py

@@ -25,6 +25,8 @@ class relation (object):
     A relation can be represented using a table
     Calling an operation and providing a non relation parameter when it is expected will
     result in a None value'''    
+    __hash__=None
+    
     def __init__(self,filename=""):
         '''Creates a relation, accepts a filename and then it will load the relation from
         that file. If no parameter is supplied an empty relation is created. Empty
@@ -185,7 +187,6 @@ class relation (object):
             if (newt.header.rename(old,new)) == False:
                 return None
         
-        #TODO only copy the link and mark the new relation as read only
         newt.content=self.content
         newt._readonly=True
         return newt
@@ -511,9 +512,13 @@ class header (object):
     '''This class defines the header of a relation.
     It is used within relations to know if requested operations are accepted'''
     
+    #Since relations are mutalbe we explicitly block hashing them
+    __hash__=None
+    
     def __init__(self,attributes):
         '''Accepts a list with attributes' names. Names MUST be unique'''
         self.attributes=attributes
+        
     def __repr__(self):
         return "header(%s)" % (self.attributes.__repr__())
         

relational/rtypes.py

@@ -54,6 +54,8 @@ class rdate (object):
         self.weekday=self.intdate.weekday()
         self.year=self.intdate.year
     
+    def __hash__(self):
+        return self.intdate.__hash__()
     def __str__(self):
         return self.intdate.__str__()
     def __add__(self,days):