装饰器 python
时间: 2023-11-05 22:00:16 浏览: 43
装饰器是Python中一种常用的语法糖形式,用于改变被装饰函数或方法的功能和性质。在Python中,装饰器以@符号开头,比如@classmethod、@staticmethod、@property等。装饰器可以通过定义一个高阶函数来实现,这个高阶函数接收一个函数作为参数,并返回一个新的函数。新的函数可以在调用原函数之前或之后执行一些额外的操作。
在引用中的例子中,@timmer是一个装饰器,它用于计算被装饰函数的执行时间。当调用被装饰的函数home时,实际上是调用了装饰器返回的新函数wrapper,这个新函数在执行被装饰函数之前记录了开始时间,执行了被装饰函数,然后记录了结束时间,并打印出执行时间。
装饰器的作用可以有很多,比如日志记录、性能分析、缓存等。通过使用装饰器,可以在不改变原函数代码的情况下给函数添加额外的功能。
相关问题
给出测试类装饰器 python的代码
这是一个属于技术范畴的问题,我可以为你提供测试类装饰器 Python 代码:
```python
import unittest
def test_decorator(cls):
for name, method in cls.__dict__.items():
if name.startswith("test"):
test_func = method
def wrapper(*args, **kwargs):
try:
print(f"[Running] {cls.__name__}.{name}")
test_func(*args, **kwargs)
print(f"[Pass] {cls.__name__}.{name}")
except AssertionError:
print(f"[Fail] {cls.__name__}.{name}")
setattr(cls, name, wrapper)
return cls
@test_decorator
class TestStringMethods(unittest.TestCase):
def test_upper(self):
self.assertEqual('foo'.upper(), 'FOO')
def test_isupper(self):
self.assertTrue('FOO'.isupper())
self.assertFalse('Foo'.isupper())
def test_split(self):
s = 'hello world'
self.assertEqual(s.split(), ['hello', 'world'])
with self.assertRaises(TypeError):
s.split(2)
if __name__ == '__main__':
unittest.main()
```
这是一个基于 unittest 模块的测试类装饰器,可以自动运行测试方法并输出测试结果。
测试类装饰器 python,给出代码
Sure, here's an example of a test class decorator in Python:
```
def skipIf(condition):
def decorator(test_item):
if condition:
def skip(*args, **kwargs):
print("Skipping test: {}".format(test_item.__name__))
return skip
else:
return test_item
return decorator
@skipIf(True)
def test_example():
assert 1 + 1 == 2
```
In this example, we define a decorator `skipIf` that takes a `condition` as input. The decorator itself is defined as a nested function `decorator` that takes a `test_item` as input (which, in our example, is a test function).
If the `condition` is `True`, then the `decorator` returns a new function `skip` that simply prints a message saying that the test is being skipped. Otherwise, the `decorator` simply returns the original `test_item` function.
Finally, we use the decorator on our test function `test_example` by putting an `@skipIf(True)` decorator before the function definition. This will cause the test to be skipped when the condition is `True` (which, in our example, it is).