From: Armin Ronacher <armin.ronacher@active-4.com>
Date: Mon, 20 May 2013 00:53:10 +0000 (+0100)
Subject: Added an explanation for how with_metaclass works
X-Git-Tag: 2.7~20
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=285c955921744873a3955091b09baf0c710ad58f;p=thirdparty%2Fjinja.git

Added an explanation for how with_metaclass works
---

diff --git a/jinja2/_compat.py b/jinja2/_compat.py
index 5d4fba54..2a0e6ed8 100644
--- a/jinja2/_compat.py
+++ b/jinja2/_compat.py
@@ -82,6 +82,15 @@ except NameError:
 
 
 def with_metaclass(meta, *bases):
+    # This requires a bit of explanation: the basic idea is to make a
+    # dummy metaclass for one level of class instanciation that replaces
+    # itself with the actual metaclass.  Because of internal type checks
+    # we also need to make sure that we downgrade the custom metaclass
+    # for one level to something closer to type (that's why __call__ and
+    # __init__ comes back from type etc.).
+    #
+    # This has the advantage over six.with_metaclass in that it does not
+    # introduce dummy classes into the final MRO.
     class __metaclass__(meta):
         __call__ = type.__call__
         __init__ = type.__init__