This article describes how to use python function modifier @ resolution, the text introduced by the sample code is very detailed, with some reference value of learning for all of us to learn or work, a friend in need can refer to the
python function of modifier @ It is to increase additional functionality to existing functions, used for insertion logs, performance test, the transaction processing and the like.
Rules create a function modifier:
(1) is a function modifier
(2) be modified to take modifier function parameters
(3) returns a new function modifier
(4) Maintenance modifier function signature is maintained
Example 1: was modified with no arguments
def log(func):
def wrapper():
print('log开始 ...')
func()
print('log结束 ...')
return wrapper
@log
def test():
print('test ..')
test()
operation result:
log开始 ...
test ..
log结束 ...
Example 2: Use property modification function module provides a method functools wraps
def log(func):
def wrapper():
print('log开始 ...')
func()
print('log结束 ...')
return wrapper
@log
def test1():
print('test1 ..')
def test2():
print('test2 ..')
print(test1.__name__)
print(test2.__name__)
operation result:
wrapper
test2
Test1 function name becomes visible, and if some of the code used will be a problem, a function may be used to modify the properties functools module provides a method wraps
from functools import wraps
def log(func):
@wraps(func)
def wrapper():
print('log开始 ...')
func()
print('log结束 ...')
return wrapper
@log
def test1():
print('test1 ..')
def test2():
print('test2 ..')
print(test1.__name__)
print(test2.__name__)
operation result:
test1
test2
Example 3: Function parameters are modified
from functools import wraps
def log(func):
@wraps(func)
def wrapper(*args,**kwargs):
print('log开始 ...',func.__name__)
ret = func(*args,**kwargs)
print('log结束 ...')
return ret
return wrapper
@log
def test1(s):
print('test1 ..', s)
return s
@log
def test2(s1, s2):
print('test2 ..', s1, s2)
return s1 + s2
test1('a')
test2('a','bc')
operation result:
log开始 ... test1
test1 .. a
log结束 ...
log开始 ... test2
test2 .. a bc
log结束 ...
Example 4: modifier parameters, requires more than the above example a multi-layer packaging
from functools import wraps
def log(arg):
def _log(func):
@wraps(func)
def wrapper(*args,**kwargs):
print('log开始 ...',func.__name__, arg)
ret = func(*args,**kwargs)
print('log结束 ...')
return ret
return wrapper
return _log
@log('module1')
def test1(s):
print('test1 ..', s)
return s
@log('module1')
def test2(s1, s2):
print('test2 ..', s1, s2)
return s1 + s2
test1('a')
test2('a','bc')
operation result:
log开始 ... test1 module1
test1 .. a
log结束 ...
log开始 ... test2 module1
test2 .. a bc
log结束 ...
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