@yaml_info can not be used on subclasses of YamlObject2 anymore as it could lead to an unexpected behaviour. Fixes #15

Author: Sylvain MARIE

yamlable/main.py

@@ -197,10 +197,14 @@ class Foo(YamlAble):
         raise ValueError("One non-None `yaml_tag` or `yaml_tag_ns` must be provided.")
 
     if issubclass(cls, YamlObject2):
-        if not yaml_tag.startswith('!'):
-            raise ValueError("When extending YamlObject2, the `yaml_tag` field should contain the full yaml tag, "
-                             "and should therefore start with !")
-        cls.yaml_tag = yaml_tag
+        # Do not support this, because the `YamlObject` metaclass needs the tag to be present BEFORE this decorator is
+        # even called. So if we are here, it means that we are trying to override a yaml_tag that was already registered
+        # with pyyaml. Too late!
+        raise TypeError("This is not supported")
+        # if not yaml_tag.startswith('!'):
+        #     raise ValueError("When extending YamlObject2, the `yaml_tag` field should contain the full yaml tag, "
+        #                      "and should therefore start with !")
+        # cls.yaml_tag = yaml_tag
 
     elif issubclass(cls, YamlAble):
         if yaml_tag.startswith('!'):

yamlable/tests/test_yamlobjects.py

@@ -1,7 +1,7 @@
 from copy import copy
 try:  # python 3.5+
     from typing import Dict, Any
-    from yamlable import Y
+    from yamlable import Y, yaml_info
 except ImportError:
     pass
 
@@ -86,6 +86,14 @@ class AbstractFooE(YamlObject2):
         #     e.dumps_yaml()
 
 
+def test_decorator():
+    """Test that the decorator can not be used when subclassing CustomFoo3"""
+    with pytest.raises(TypeError):
+        @yaml_info("!hello_dear")
+        class CustomFoo3(YamlObject2):
+            pass
+
+
 def test_abstract_parent():
     """This tests that we can define an abstract parent class with the YamlAble behaviour and inherit it"""