From 7f86cfe1ccaf9b2c5fc719336c4b990004cd1c62 Mon Sep 17 00:00:00 2001
From: Bertrand Bordage <bordage.bertrand@gmail.com>
Date: Thu, 18 Jun 2015 03:07:04 +0200
Subject: [PATCH] Python optimisations.

---
 cachalot/monkey_patch.py |  8 +++++---
 cachalot/utils.py        | 10 +++++-----
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/cachalot/monkey_patch.py b/cachalot/monkey_patch.py
index 1f06970..f89e11f 100644
--- a/cachalot/monkey_patch.py
+++ b/cachalot/monkey_patch.py
@@ -47,6 +47,9 @@ def _unset_raw_connection(original):
     return inner
 
 
+TUPLE_OR_LIST = (tuple, list)
+
+
 def _get_result_or_execute_query(execute_query_func, cache_key,
                                  table_cache_keys):
     cache = cachalot_caches.get_cache()
@@ -68,8 +71,7 @@ def _get_result_or_execute_query(execute_query_func, cache_key,
             return result
 
     result = execute_query_func()
-    if isinstance(result, Iterable) \
-            and not isinstance(result, (tuple, list)):
+    if isinstance(result, Iterable) and result.__class__ not in TUPLE_OR_LIST:
         result = list(result)
 
     cache.set(cache_key, (time(), result), None)
@@ -83,7 +85,7 @@ def _patch_compiler(original):
     def inner(compiler, *args, **kwargs):
         execute_query_func = lambda: original(compiler, *args, **kwargs)
         if not cachalot_settings.CACHALOT_ENABLED \
-                or isinstance(compiler, WRITE_COMPILERS):
+                or compiler.__class__ in WRITE_COMPILERS:
             return execute_query_func()
 
         try:
diff --git a/cachalot/utils.py b/cachalot/utils.py
index 8434805..88c6e96 100644
--- a/cachalot/utils.py
+++ b/cachalot/utils.py
@@ -70,8 +70,8 @@ def _get_tables_from_sql(connection, lowercased_sql):
 
 def _find_subqueries(children):
     for child in children:
-        if isinstance(child, SubqueryConstraint):
-            if isinstance(child.query_object, Query):
+        if child.__class__ is SubqueryConstraint:
+            if child.query_object.__class__ is Query:
                 yield child.query_object
             else:
                 yield child.query_object.query
@@ -80,9 +80,9 @@ def _find_subqueries(children):
             if DJANGO_GTE_1_7:
                 if hasattr(child, 'rhs'):
                     rhs = child.rhs
-            elif isinstance(child, tuple):
+            elif child.__class__ is tuple:
                 rhs = child[-1]
-            if isinstance(rhs, Query):
+            if rhs.__class__ is Query:
                 yield rhs
             elif hasattr(rhs, 'query'):
                 yield rhs.query
@@ -102,7 +102,7 @@ def _get_tables(query, db_alias):
     for subquery in subquery_constraints:
         tables.update(_get_tables(subquery, db_alias))
     if query.extra_select or hasattr(query, 'subquery') \
-            or any(isinstance(c, ExtraWhere) for c in query.where.children):
+            or any(c.__class__ is ExtraWhere for c in query.where.children):
         sql = query.get_compiler(db_alias).as_sql()[0].lower()
         additional_tables = _get_tables_from_sql(connections[db_alias], sql)
         tables.update(additional_tables)