revert default and use 'None' instead

tests/po_lib/__init__.py

@@ -35,13 +35,13 @@ class POTopLevelOverriden2(ItemPage):
 class POTopLevel1(POBase):
     expected_instead_of = POTopLevelOverriden1
     expected_patterns = Patterns(["example.com"], ["/*.jpg|"], priority=300)
-    expected_to_return = dict
+    expected_to_return = None
     expected_meta = {}  # type: ignore
 
 
 @handle_urls("example.com", instead_of=POTopLevelOverriden2)
 class POTopLevel2(POBase):
     expected_instead_of = POTopLevelOverriden2
     expected_patterns = Patterns(["example.com"])
-    expected_to_return = dict
+    expected_to_return = None
     expected_meta = {}  # type: ignore

tests/po_lib/a_module.py

@@ -12,5 +12,5 @@ class POModuleOverriden(ItemPage):
 class POModule(POBase):
     expected_instead_of = POModuleOverriden
     expected_patterns = Patterns(["example.com"])
-    expected_to_return = dict
+    expected_to_return = None
     expected_meta = {"extra_arg": "foo"}  # type: ignore

tests/po_lib/nested_package/__init__.py

@@ -16,5 +16,5 @@ class PONestedPkgOverriden(ItemPage):
 class PONestedPkg(POBase):
     expected_instead_of = PONestedPkgOverriden
     expected_patterns = Patterns(["example.com", "example.org"], ["/*.jpg|"])
-    expected_to_return = dict
+    expected_to_return = None
     expected_meta = {}  # type: ignore

tests/po_lib/nested_package/a_nested_module.py

@@ -18,5 +18,5 @@ class PONestedModule(POBase):
     expected_patterns = Patterns(
         include=["example.com", "example.org"], exclude=["/*.jpg|"]
     )
-    expected_to_return = dict
+    expected_to_return = None
     expected_meta = {}  # type: ignore

tests/po_lib_sub/__init__.py

@@ -22,5 +22,5 @@ class POLibSubOverriden(ItemPage):
 class POLibSub(POBase):
     expected_instead_of = POLibSubOverriden
     expected_patterns = Patterns(["sub.example"])
-    expected_to_return = dict
+    expected_to_return = None
     expected_meta = {}  # type: ignore

tests/po_lib_to_return/__init__.py

@@ -32,7 +32,7 @@ class SomePage(ItemPage):
 
     expected_instead_of = None
     expected_patterns = Patterns(["example.com"])
-    expected_to_return = dict
+    expected_to_return = None
     expected_meta = {}
 
     @field

web_poet/_typing.py

@@ -24,7 +24,7 @@ def get_generic_parameter(cls):
             return args[0]
 
 
-def get_item_cls(cls, default=dict):
+def get_item_cls(cls, default=None):
     param = get_generic_parameter(cls)
     if param is None or isinstance(param, typing.TypeVar):  # class is not parametrized
         return default

web_poet/pages.py

@@ -47,7 +47,7 @@ class Returns(typing.Generic[ItemT]):
     @property
     def item_cls(self) -> typing.Type[ItemT]:
         """Item class"""
-        return get_item_cls(self.__class__)
+        return get_item_cls(self.__class__, default=dict)
 
 
 class ItemPage(Injectable, Returns[ItemT]):

web_poet/rules.py

@@ -46,9 +46,16 @@ class ApplyRule:
           This doesn't do anything for now but may be useful for future API updates.
 
     The main functionality of this class lies in the ``instead_of`` and ``to_return``
-    parameter. Should both of these be omitted, then :class:`~.ApplyRule` simply
+    parameters. Should both of these be omitted, then :class:`~.ApplyRule` simply
     tags which URL patterns the given Page Object is expected to be used.
 
+    As much as possible, the ``to_return`` parameter should capture the Item Class
+    that the Page Object is capable of returning. Before passing it to :class:`~.ApplyRule`,
+    the ``to_return`` value is primarily derived from the return class specified
+    from Page Objects that are subclasses of :class:`~.ItemPage`. However, a
+    special case exists when a Page Object returns a ``dict`` as an item but then
+    the rule should have ``to_return=None`` and **NOT** ``to_return=dict``.
+
     More information regarding its usage in :ref:`intro-overrides`.
 
     .. tip::