[Python-checkins] Add more tests for the descriptor tutorial (GH-25164)

Sat Apr 3 16:08:16 EDT 2021

https://github.com/python/cpython/commit/e4c8895ee5457b11f52841b79b51f3c3d6373fef
commit: e4c8895ee5457b11f52841b79b51f3c3d6373fef
branch: master
author: Raymond Hettinger <rhettinger at users.noreply.github.com>
committer: rhettinger <rhettinger at users.noreply.github.com>
date: 2021年04月03日T13:07:52-07:00
summary:
Add more tests for the descriptor tutorial (GH-25164)
files:
M Doc/howto/descriptor.rst

diff --git a/Doc/howto/descriptor.rst b/Doc/howto/descriptor.rst
index 420d9b94306ea..819401ea1385c 100644
--- a/Doc/howto/descriptor.rst
+++ b/Doc/howto/descriptor.rst
@@ -281,7 +281,9 @@ The new class now logs access to both *name* and *age*:
 INFO:root:Updating 'name' to 'Catherine C'
 INFO:root:Updating 'age' to 20
 
-The two *Person* instances contain only the private names::
+The two *Person* instances contain only the private names:
+
+.. doctest::
 
 >>> vars(pete)
 {'_name': 'Peter P', '_age': 10}
@@ -710,6 +712,38 @@ perform attribute lookup by way of a helper function:
 raise
 return type(obj).__getattr__(obj, name) # __getattr__
 
+.. doctest::
+ :hide:
+
+
+ >>> class ClassWithGetAttr:
+ ... x = 123
+ ... def __getattr__(self, attr):
+ ... return attr.upper()
+ ...
+ >>> cw = ClassWithGetAttr()
+ >>> cw.y = 456
+ >>> getattr_hook(cw, 'x')
+ 123
+ >>> getattr_hook(cw, 'y')
+ 456
+ >>> getattr_hook(cw, 'z')
+ 'Z'
+
+ >>> class ClassWithoutGetAttr:
+ ... x = 123
+ ...
+ >>> cwo = ClassWithoutGetAttr()
+ >>> cwo.y = 456
+ >>> getattr_hook(cwo, 'x')
+ 123
+ >>> getattr_hook(cwo, 'y')
+ 456
+ >>> getattr_hook(cwo, 'z')
+ Traceback (most recent call last):
+ ...
+ AttributeError: 'ClassWithoutGetAttr' object has no attribute 'z'
+
 So if :meth:`__getattr__` exists, it is called whenever :meth:`__getattribute__`
 raises :exc:`AttributeError` (either directly or in one of the descriptor calls).
 
@@ -1139,8 +1173,8 @@ If you have ever wondered where *self* comes from in regular methods or where
 *cls* comes from in class methods, this is it!
 
 
-Other kinds of methods
-----------------------
+Kinds of methods
+----------------
 
 Non-data descriptors provide a simple mechanism for variations on the usual
 patterns of binding functions into methods.
@@ -1193,19 +1227,19 @@ example calls are unexciting:
 class E:
 @staticmethod
 def f(x):
- print(x)
+ return x * 10
 
 .. doctest::
 
 >>> E.f(3)
- 3
+ 30
 >>> E().f(3)
- 3
+ 30
 
 Using the non-data descriptor protocol, a pure Python version of
 :func:`staticmethod` would look like this:
 
-.. doctest::
+.. testcode::
 
 class StaticMethod:
 "Emulate PyStaticMethod_Type() in Objects/funcobject.c"
@@ -1216,6 +1250,22 @@ Using the non-data descriptor protocol, a pure Python version of
 def __get__(self, obj, objtype=None):
 return self.f
 
+.. testcode::
+ :hide:
+
+ class E_sim:
+ @StaticMethod
+ def f(x):
+ return x * 10
+
+.. doctest::
+ :hide:
+
+ >>> E_sim.f(3)
+ 30
+ >>> E_sim().f(3)
+ 30
+
 
 Class methods
 -------------
