From eac47766844b90e7d3269e7a8c012eee34ec0093 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Anssi=20K=C3=A4=C3=A4ri=C3=A4inen?= <akaariai@gmail.com>
Date: Sun, 1 Dec 2013 02:22:30 +0200
Subject: [PATCH] Minor cleanup of Lookup API

---
 django/db/models/lookups.py | 11 +----------
 docs/ref/models/lookups.txt | 15 ++++-----------
 2 files changed, 5 insertions(+), 21 deletions(-)

diff --git a/django/db/models/lookups.py b/django/db/models/lookups.py
index b096a20e88..010d77a76a 100644
--- a/django/db/models/lookups.py
+++ b/django/db/models/lookups.py
@@ -1,6 +1,5 @@
 from copy import copy
 
-from django.core.exceptions import FieldError
 from django.conf import settings
 from django.utils import timezone
 from django.utils.functional import cached_property
@@ -29,18 +28,10 @@ class Extract(object):
 
 class Lookup(object):
     lookup_name = None
-    extract_class = None
 
     def __init__(self, lhs, rhs):
         self.lhs, self.rhs = lhs, rhs
-        if rhs is None:
-            if not self.extract_class:
-                raise FieldError("Lookup '%s' doesn't support nesting." % self.lookup_name)
-        else:
-            self.rhs = self.get_prep_lookup()
-
-    def get_extract(self):
-        return self.extract_class(self.lhs)
+        self.rhs = self.get_prep_lookup()
 
     def get_prep_lookup(self):
         return self.lhs.output_type.get_prep_lookup(self.lookup_name, self.rhs)
diff --git a/docs/ref/models/lookups.txt b/docs/ref/models/lookups.txt
index b5dc5c20d1..959c70cb14 100644
--- a/docs/ref/models/lookups.txt
+++ b/docs/ref/models/lookups.txt
@@ -93,16 +93,9 @@ The process_rhs method is used to convert the right hand side into query string.
 The rhs is the value given in the filter clause. It can be a raw value to
 compare agains, a F() reference to another field or even a QuerySet.
 
-.. method:: get_extract()
-
-The get_extract method is used in nested lookups. It must return an Extract instance.
-
-.. classattribute:: Lookup.extract_class
-
-The default implementation of get_extract() will return an instance of extract_class.
-
-In addition there are some private methods - that is, implementing just the above
-mentioned attributes and methods is not enough, you must subclass Lookup instead.
+In addition the Lookup class has some private methods - that is, implementing
+just the above mentioned attributes and methods is not enough, instead you
+should subclass Lookup.
 
 The Extract class
 ~~~~~~~~~~~~~~~~~
@@ -112,7 +105,7 @@ For example you could have an Extract that procudes modulo 3 of the given value.
 In SQL this would be something like "author"."age" % 3.
 
 Extracts are used in nested lookups. The Extract class must implement the query
-part interface.
+part interface. In addition the Extract should must lookup_name attribute.
 
 A simple Lookup example
 ~~~~~~~~~~~~~~~~~~~~~~~