Question

在this blog article中，他们使用构造：

  @measured
  def some_func():
    #...
  # Presumably outputs something like "some_func() is finished in 121.333 s" somewhere

这个@measured指令似乎不适用于原始python。它是什么？

更新：我从Triptych看到@something是有效的，但我在哪里可以找到@measured，是在某个地方的某个库中，还是这个博客的作者使用他自己私人的东西代码库？

Answer 1

@measured使用名为measured的函数或类来装饰some_func（）函数。 @是装饰器语法，measured是装饰器函数名称。

装饰器可能有点难以理解，但它们基本上用于将代码包装在函数周围，或者将代码注入其中。

例如，测量函数（用作装饰器）可能就像这样实现......

import time

def measured(orig_function):
    # When you decorate a function, the decorator func is called
    # with the original function as the first argument.
    # You return a new, modified function. This returned function
    # is what the to-be-decorated function becomes.

    print "INFO: This from the decorator function"
    print "INFO: I am about to decorate %s" % (orig_function)

    # This is what some_func will become:
    def newfunc(*args, **kwargs):
        print "INFO: This is the decorated function being called"

        start = time.time()

        # Execute the old function, passing arguments
        orig_func_return = orig_function(*args, **kwargs)
        end = time.time()

        print "Function took %s seconds to execute" % (end - start)
        return orig_func_return # return the output of the original function

    # Return the modified function, which..
    return newfunc

@measured
def some_func(arg1):
    print "This is my original function! Argument was %s" % arg1

# We call the now decorated function..
some_func(123)

#.. and we should get (minus the INFO messages):
This is my original function! Argument was 123
# Function took 7.86781311035e-06 to execute

装饰器语法只是一种更简洁，更简洁的方法：

def some_func():
    print "This is my original function!"

some_func = measured(some_func)

Python中包含一些装饰器，例如staticmethod - 但measured不是其中之一：

>>> type(measured)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'measured' is not defined

检查项目import语句，以查看函数或类的来源。如果它使用from blah import *，您需要检查所有这些文件（这是不鼓励import *的原因），或者您可以执行grep -R def measured *

之类的操作

Answer 2

是的，这是真的。这是一个功能装饰者。

Python中的函数修饰器是将函数作为单个参数的函数，并在其中返回一个新函数。

@classmethod和@staticmethod是两个内置函数装饰器。

@measured是标准的装饰者吗？它在哪个图书馆？

3 个答案: