[Sqlalchemy-tickets] Issue #3383: Mapper setup does not run __declare_first__ or __declare_last__ in mixins anymore (zzzeek/sqlalchemy)

[Thorsten L. <iss...@bi...>]

New issue 3383: Mapper setup does not run __declare_first__ or __declare_last__ in mixins anymore
https://bitbucket.org/zzzeek/sqlalchemy/issue/3383/mapper-setup-does-not-run

Thorsten Lockert:

Handling of `__declare_first__` and `__declare_last__` (as used in e.g. the [PyCon 2014 ATM sample](https://bitbucket.org/zzzeek/pycon2014_atmcraft)) got broken with commit 7f82c55.

One potential fix is the fragment below, but I am not convinced this is correct:

```patch
--- ext/declarative/base.py   2015-04-23 20:27:08.000000000 -0700
+++ ext/declarative/base.py   2015-04-23 22:27:52.000000000 -0700
@@ -66,11 +66,10 @@

     for base in cls.__mro__:
         _is_declarative_inherits = hasattr(base, '_decl_class_registry')
-        if attrname in base.__dict__:
+        if attrname in base.__dict__ and (
+                base is cls or not _is_declarative_inherits):
             value = getattr(base, attrname)
-            if (base is cls or
-                    (base in cls.__bases__ and not _is_declarative_inherits)):
-                return value
+            return value
     else:
         return None

```

Responsible: zzzeek