doctests

python · JelleZijlstra · Jul 28, 2025 · Jul 20, 2025 · Jul 21, 2025 · Jul 22, 2025
commit ca07bc9f84297b09430ab35cf1ad9db405496d96
@@ -1501,10 +1501,13 @@ Multiple inheritance
 Python classes may have multiple base classes, a technique known as
 *multiple inheritance*.  The base classes are specified in the class definition
 by listing them in parentheses after the class name, separated by commas.
-For example, the following class definition::
+For example, the following class definition:
 
-   class C(A, B):
-       pass
+.. doctest::
+
+   >>> class A: pass
+   >>> class B: pass
+   >>> class C(A, B): pass
 
 defines a class ``C`` that inherits from classes ``A`` and ``B``.
 
@@ -1518,18 +1521,28 @@ cannot be created, if no valid metaclass can be determined, or if there is an in
 layout conflict. We'll discuss each of these in turn.
 
 First, all base classes must allow subclassing. While most classes allow subclassing,
-some built-in classes do not, such as :class:`bool`::
+some built-in classes do not, such as :class:`bool`:
 
-   class SubBool(bool):  # TypeError
-       pass
+.. doctest::
+
+   >>> class SubBool(bool):  # TypeError
+   ...    pass
+   Traceback (most recent call last):
+      ...
+   TypeError: type 'bool' is not an acceptable base type
 
 To create a consistent MRO, all bases appear in the order
 they were specified in the base class list and every child class must appear before its
-base classes. Below is an example where this fails::
+base classes. Below is an example where this fails:
+
+.. doctest::
 
-   class Base: pass
-   class Child(Base): pass
-   class Grandchild(Base, Child): pass  # TypeError
+   >>> class Base: pass
+   >>> class Child(Base): pass
+   >>> class Grandchild(Base, Child): pass  # TypeError
+   Traceback (most recent call last):
+      ...
+   TypeError: Cannot create a consistent method resolution order (MRO) for bases Base, Child
 
 In the MRO of ``Grandchild``, ``Child`` must appear before ``Base`` because it is first
 in the base class list, but it must also appear after ``Base`` because it is a child of
@@ -1558,31 +1571,36 @@ for each base class to produce a list of candidate solid bases. If there is a un
 that is a subclass of all others, then that class is the solid base. Otherwise, class creation
 fails.
 
-Example::
-
-   class Solid1:
-      __slots__ = ("solid1",)
-
-   class Solid2:
-      __slots__ = ("solid2",)
-
-   class SolidChild(Solid1):
-      __slots__ = ("solid_child",)
-
-   class C1:  # solid base is `object`
-      pass
-
-   # OK: solid bases are `Solid1` and `object`, and `Solid1` is a subclass of `object`.
-   class C2(Solid1, C1):  # solid base is `Solid1`
-      pass
-
-   # OK: solid bases are `SolidChild` and `Solid1`, and `SolidChild` is a subclass of `Solid1`.
-   class C3(SolidChild, Solid1):  # solid base is `SolidChild`
-      pass
-
-   # Error: solid bases are `Solid1` and `Solid2`, but they are not subclasses of each other.
-   class C4(Solid1, Solid2):  # error: no single solid base
-      pass
+Example:
+
+.. doctest::
+
+   >>> class Solid1:
+   ...    __slots__ = ("solid1",)
+   >>>
+   >>> class Solid2:
+   ...    __slots__ = ("solid2",)
+   >>>
+   >>> class SolidChild(Solid1):
+   ...    __slots__ = ("solid_child",)
+   >>>
+   >>> class C1:  # solid base is `object`
+   ...    pass
+   >>>
+   >>> # OK: solid bases are `Solid1` and `object`, and `Solid1` is a subclass of `object`.
+   >>> class C2(Solid1, C1):  # solid base is `Solid1`
+   ...    pass
+   >>>
+   >>> # OK: solid bases are `SolidChild` and `Solid1`, and `SolidChild` is a subclass of `Solid1`.
+   >>> class C3(SolidChild, Solid1):  # solid base is `SolidChild`
+   ...    pass
+   >>>
+   >>> # Error: solid bases are `Solid1` and `Solid2`, but they are not subclasses of each other.
+   >>> class C4(Solid1, Solid2):  # error: no single solid base
+   ...    pass
+   Traceback (most recent call last):
+     ...
+   TypeError: multiple bases have instance lay-out conflict
 
 .. _async: