- Minor changes to comments

git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@313 014f5005-505e-4b48-8d0a-63407b615a7c

relational/maintenance.py

@@ -48,6 +48,8 @@ def check_latest_version():
     
     #html
     s=r.read()
+    if len(s)==0:
+        return None
     
     l= s[s.find('<ul>')+4:s.find('</ul>')].split('\n')
     l.sort()

relational/optimizer.py

@@ -50,8 +50,7 @@ def optimize_all(expression,rels,specific=True,general=True,debug=None):
     general: True if it has to perform general optimizations
     debug: if a list is provided here, after the end of the function, it
         will contain the query repeated many times to show the performed
-        steps. Of course don't call optimize_all(... ,debug=[]) because it
-        would make no sense
+        steps.
     
     Return value: this will return an optimized version of the expression'''
     if isinstance(expression,str):

relational/parser.py

@@ -85,7 +85,7 @@ class node (object):
         '''Expression from right to left, searching for binary operators
         this means that binary operators have lesser priority than
         unary operators.
-        It find the operator with lesser priority, uses it as root of this
+        It finds the operator with lesser priority, uses it as root of this
         (sub)tree using everything on its left as left parameter (so building
         a left subtree with the part of the list located on left) and doing 
         the same on right.

relational/relation.py

@@ -129,7 +129,7 @@ class relation (object):
     def product (self,other):
         '''Cartesian product, attributes must be different to avoid collisions
         Doing this operation on relations with colliding attributes will 
-        cause the return of a None value.
+        cause an exception.
         It is possible to use rename on attributes and then use the product'''
         
         if (self.__class__!=other.__class__)or(self.header.sharedAttributes(other.header)!=0):