Clarify need for attr.ib for attr decorator validators

Ref #466
python-attrs · Oct 1, 2019 · f083cd7 · f083cd7
1 parent 08bbaab
commit f083cd7
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/docs/examples.rst b/docs/examples.rst
@@ -423,6 +423,8 @@ You can use a decorator:
       ...
    ValueError: value out of bounds
 
+Please note that the decorator approach only works if -- and only if! -- the attribute in question has an ``attr.ib`` assigned.
+Therefore if you use ``@attr.s(auto_attribs=True)``, it is *not* enough to decorate said attribute with a type.
 
 ``attrs`` ships with a bunch of validators, make sure to `check them out <api_validators>` before writing your own: