From 0a562ff6036ea97dfe6b0ec5d602f19587574066 Mon Sep 17 00:00:00 2001
From: Salvo 'LtWorf' Tomaselli <tiposchi@tiscali.it>
Date: Mon, 23 Feb 2015 14:17:50 +0100
Subject: [PATCH] Check for duplicated attributes

Fails to work if attributes are duplicated, raising an appropriate
exception.
---
 relational/relation.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/relational/relation.py b/relational/relation.py
index 09c166e..858d59f 100644
--- a/relational/relation.py
+++ b/relational/relation.py
@@ -527,6 +527,9 @@ class header (object):
             if not is_valid_relation_name(i):
                 raise Exception('"%s" is not a valid attribute name' % i)
 
+        if len(attributes) != len(set(attributes)):
+            raise Exception('Attribute names must be unique')
+
     def __repr__(self):
         return "header(%s)" % (self.attributes.__repr__())