From 8f4cd59c9ae98c90cf7cd8e50040f99573dff7d8 Mon Sep 17 00:00:00 2001
From: Stefan Wehrmeyer <mail@stefanwehrmeyer.com>
Date: Fri, 31 Jan 2014 20:42:04 +0100
Subject: [PATCH] Treat columns as ordered throughout code

The set() does not make anything any easier,
lists are closer to underlying representation.
---
 dataset/persistence/table.py | 7 +++++--
 docs/quickstart.rst          | 4 ++--
 test/test_persistence.py     | 3 +--
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/dataset/persistence/table.py b/dataset/persistence/table.py
index 55c294c..a36a9c9 100644
--- a/dataset/persistence/table.py
+++ b/dataset/persistence/table.py
@@ -25,7 +25,7 @@ class Table(object):
         """
         Get a listing of all columns that exist in the table.
         """
-        return set(self.table.columns.keys())
+        return list(self.table.columns.keys())
 
     def drop(self):
         """
@@ -184,7 +184,10 @@ class Table(object):
         self.database.executable.execute(stmt)
 
     def _ensure_columns(self, row, types={}):
-        for column in set(row.keys()) - set(self.table.columns.keys()):
+        # Keep order of inserted columns
+        for column in row.keys():
+            if column in self.table.columns.keys():
+                continue
             if column in types:
                 _type = types[column]
             else:
diff --git a/docs/quickstart.rst b/docs/quickstart.rst
index 612ddbe..520468f 100644
--- a/docs/quickstart.rst
+++ b/docs/quickstart.rst
@@ -76,8 +76,8 @@ database:
 
 Now, let's list all columns available in the table ``user``:
 
-   >>> print db['user'].columns
-   set([u'id', u'name', u'email', u'pwd', u'country'])
+   >>> print(db['user'].columns)
+   [u'id', u'name', u'email', u'pwd', u'country']
 
 Using ``len()`` we can get the total number of rows in a table:
 
diff --git a/test/test_persistence.py b/test/test_persistence.py
index 6ee319f..1d9a0f8 100644
--- a/test/test_persistence.py
+++ b/test/test_persistence.py
@@ -229,8 +229,7 @@ class TableTestCase(unittest.TestCase):
 
     def test_columns(self):
         cols = self.tbl.columns
-        assert isinstance(cols, set), 'columns should be a set'
-        assert len(cols) == 4, 'column count mismatch'
+        assert len(list(cols)) == 4, 'column count mismatch'
         assert 'date' in cols and 'temperature' in cols and 'place' in cols
 
     def test_iter(self):