Python's Functools module

This module provides 3 interesting functions, which are described below for their usage.

The first is the partial function, which can rebind the optional parameters of the function to generate a callable partial object

2. >>> Int (' ten') # is actually equivalent to int (' Ten ', base=10) and int (' Ten ', ten)
4. Ten
6. >>> Int (' ten ', 2) # is actually an abbreviation for int (' Ten ', base=2)
8. 2
10. >>> from functools import partial
12. >>> int2 = partial (int, 2) # I didn't write base here, and it went wrong.
14. >>> Int2 (' ten ')
16. Traceback (most recent):
18. File "<stdin>", line 1, in <module>
20. Typeerror:an integer is required
22. >>> int2 = partial (int, base=2) # bind the base parameter to the Int2 function
24. >>> int2 (' ten ') # Now the default parameter base is set to 2
26. 2
28. >>> Int2 (' Ten ', 3) # without base, the result is wrong
30. Traceback (most recent):
32. File "<stdin>", line 1, in <module>
34. typeerror:keyword parameter ' base ' was given by position and by name
36. >>> Int2 (' Ten ', base=3)
38. 3
40. >>> Type (int2)
42. <type ' functools.partial '>

As you can see, the only thing to note is that an optional parameter must write out the parameter name.

Next is the Update_wrapper function, which can copy the encapsulated function's __name__, __module__, __doc__, and __dict__ to the encapsulation function:

2. #-*-coding:gbk-*-
4.   
6. def thisisliving (fun):
8. def Living (*args, **kw):
10. return fun (*args, **kw) + ' Alive is eating. '
12. return living
14.  
16. @thisIsliving
18. def whatisliving ():
20. "What Is Alive"
22. return ' Yes, what's the life? '
24.   
26. Print whatisliving ()
28. print whatisliving.__doc__
30.   
32. print
34.   
36. From functools import update_wrapper
38. def thisisliving (fun):
40. def Living (*args, **kw):
42. return fun (*args, **kw) + ' Alive is eating. '
44. return update_wrapper (living, fun)
46.  
48. @thisIsliving
50. def whatisliving ():
52. "What Is Alive"
54. return ' Yes, what's the life? '
56.   
58. Print whatisliving ()
60. print whatisliving.__doc__

Results:

Yes

, what's the life? To live is to eat.
None

Yes, what's the life? To live is to eat.
What is Alive

However, it is not much use, after all, just a few 4 lines to write the assignment statement.

Finally, the wraps function, which encapsulates the Update_wrapper, is also included:

[Python]View Plain Copy

2. #-*-coding:gbk-*-
4.   
6. From functools import wraps
8.   
10. def thisisliving (fun):
12. @wraps(fun)
14. def Living (*args, **kw):
16. return fun (*args, **kw) + ' Alive is eating. '
18. return living
20.  
22. @thisIsliving
24. def whatisliving ():
26. "What Is Alive"
28. return ' Yes, what's the life? '
30.   
32. Print whatisliving ()
34. print whatisliving.__doc__

Python's Functools module