[Python 範例代碼] DECORATORS FOR ADDING ALIASES TO METHODS IN A CLASS

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The following recipe can be used as a means to adding aliases to methods in a class: 
- utils.py 

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1. class alias(object):  
2.     """  
3.     Alias class that can be used as a decorator for making methods callable  
4.     through other names (or "aliases").  
5.     Note: This decorator must be used inside an @aliased -decorated class.  
6.     For example, if you want to make the method shout() be also callable as  
7.     yell() and scream(), you can use alias like this:  
8.   
9.         @alias('yell', 'scream')  
10.         def shout(message):  
11.             # ....  
12.     """  
13.   
14.     def __init__(self, *aliases):  
15.         """Constructor."""  
16.         self.aliases = set(aliases)  
17.   
18.     def __call__(self, f):  
19.         """  
20.         Method call wrapper. As this decorator has arguments, this method will  
21.         only be called once as a part of the decoration process, receiving only  
22.         one argument: the decorated function ('f'). As a result of this kind of  
23.         decorator, this method must return the callable that will wrap the  
24.         decorated function.  
25.         """  
26.         f._aliases = self.aliases  
27.         return f  
28.   
29.   
30. def aliased(aliased_class):  
31.     """  
32.     Decorator function that *must* be used in combination with @alias  
33.     decorator. This class will make the magic happen!  
34.     @aliased classes will have their aliased method (via @alias) actually  
35.     aliased.  
36.     This method simply iterates over the member attributes of 'aliased_class'  
37.     seeking for those which have an '_aliases' attribute and then defines new  
38.     members in the class using those aliases as mere pointer functions to the  
39.     original ones.  
40.   
41.     Usage:  
42.         @aliased  
43.         class MyClass(object):  
44.             @alias('coolMethod', 'myKinkyMethod')  
45.             def boring_method():  
46.                 # ...  
47.   
48.         i = MyClass()  
49.         i.coolMethod() # equivalent to i.myKinkyMethod() and i.boring_method()  
50.     """  
51.     original_methods = aliased_class.__dict__.copy()  
52.     for name, method in original_methods.iteritems():  
53.         if hasattr(method, '_aliases'):  
54.             # Add the aliases for 'method', but don't override any  
55.             # previously-defined attribute of 'aliased_class'  
56.             for alias in method._aliases - set(original_methods):  
57.                 setattr(aliased_class, alias, method)  
58.     return aliased_class  

Then you can use it this way: 
- test.py 

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1. from utils import *  
2.   
3. @aliased  
4. class People:  
5.     def __init__(self, name, age):  
6.         self.name = name  
7.         self.age = age  
8.   
9.     @alias('n', 'showname')  
10.     def getname(self):  
11.         print('My name is {}'.format(self.name))  
12.   
13.     @alias('a', 'showage')  
14.     def getage(self):  
15.         print('My age is {}'.format(self.age))  
16.   
17. pe = People('John', 37)  
18. pe.getname()  
19. pe.getage()  
20. pe.n()  
21. pe.a()  

The execution result: 

# python test.py
My name is John
My age is 37
My name is John
My age is 37

Supplement 
* Python 文章收集 - A guide to Python's function decorators