Class method decorator with self arguments?
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Track title: Darkness Approaches Looping
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Chapters
00:00 Class Method Decorator With Self Arguments?
00:29 Accepted Answer Score 341
01:17 Answer 2 Score 115
01:45 Answer 3 Score 49
02:21 Answer 4 Score 17
02:58 Answer 5 Score 11
03:34 Thank you
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Full question
https://stackoverflow.com/questions/1173...
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Content licensed under CC BY-SA
https://meta.stackexchange.com/help/lice...
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Tags
#python #pythondecorators
#avk47
Rise to the top 3% as a developer or hire one of them at Toptal: https://topt.al/25cXVn
--------------------------------------------------
Music by Eric Matyas
https://www.soundimage.org
Track title: Darkness Approaches Looping
--
Chapters
00:00 Class Method Decorator With Self Arguments?
00:29 Accepted Answer Score 341
01:17 Answer 2 Score 115
01:45 Answer 3 Score 49
02:21 Answer 4 Score 17
02:58 Answer 5 Score 11
03:34 Thank you
--
Full question
https://stackoverflow.com/questions/1173...
--
Content licensed under CC BY-SA
https://meta.stackexchange.com/help/lice...
--
Tags
#python #pythondecorators
#avk47
ACCEPTED ANSWER
Score 346
Yes. Instead of passing in the instance attribute at class definition time, check it at runtime:
def check_authorization(f):
def wrapper(*args):
print args[0].url
return f(*args)
return wrapper
class Client(object):
def __init__(self, url):
self.url = url
@check_authorization
def get(self):
print 'get'
>>> Client('http://www.google.com').get()
http://www.google.com
get
The decorator intercepts the method arguments; the first argument is the instance, so it reads the attribute off of that. You can pass in the attribute name as a string to the decorator and use getattr if you don't want to hardcode the attribute name:
def check_authorization(attribute):
def _check_authorization(f):
def wrapper(self, *args):
print getattr(self, attribute)
return f(self, *args)
return wrapper
return _check_authorization
ANSWER 2
Score 118
A more concise example might be as follows:
#/usr/bin/env python3
from functools import wraps
def wrapper(method):
@wraps(method)
def _impl(self, *method_args, **method_kwargs):
method_output = method(self, *method_args, **method_kwargs)
return method_output + "!"
return _impl
class Foo:
@wrapper
def bar(self, word):
return word
f = Foo()
result = f.bar("kitty")
print(result)
Which will print:
kitty!
ANSWER 3
Score 49
from re import search
from functools import wraps
def is_match(_lambda, pattern):
def wrapper(f):
@wraps(f)
def wrapped(self, *f_args, **f_kwargs):
if callable(_lambda) and search(pattern, (_lambda(self) or '')):
f(self, *f_args, **f_kwargs)
return wrapped
return wrapper
class MyTest(object):
def __init__(self):
self.name = 'foo'
self.surname = 'bar'
@is_match(lambda x: x.name, 'foo')
@is_match(lambda x: x.surname, 'foo')
def my_rule(self):
print 'my_rule : ok'
@is_match(lambda x: x.name, 'foo')
@is_match(lambda x: x.surname, 'bar')
def my_rule2(self):
print 'my_rule2 : ok'
test = MyTest()
test.my_rule()
test.my_rule2()
ouput: my_rule2 : ok
ANSWER 4
Score 17
Another option would be to abandon the syntactic sugar and decorate in the __init__ of the class.
def countdown(number):
def countdown_decorator(func):
def func_wrapper():
for index in reversed(range(1, number+1)):
print(index)
func()
return func_wrapper
return countdown_decorator
class MySuperClass():
def __init__(self, number):
self.number = number
self.do_thing = countdown(number)(self.do_thing)
def do_thing(self):
print('im doing stuff!')
myclass = MySuperClass(3)
myclass.do_thing()
which would print
3
2
1
im doing stuff!