回复内容:
题主可能并没有理解
“在Python中,函数本身也是对象”
这一本质。那不妨慢慢来,从最基本的概念开始,讨论一下这个问题:
1. Python中一切皆对象
这恐怕是学习Python最有用的一句话。想必你已经知道Python中的list, tuple, dict等内置数据结构,当你执行:
alist = [1, 2, 3]
题主遇到的这个问题很典型,就是把修饰器当成了包装器, 认为调用 useful 前先调用 addspam。其实 useful 不是被 addspam 包装了,而是替换了。调用 useful 调用的就是 new。余下的 fn 指向原来的 useful, 才需要第一类函数、作用域继承等知识点来理解。可变参数 *args 则是干扰的另外一个知识点,替换成 x, y 就行了。
Python里面的@只是一个syntax sugar而已,在你声明useful的时候,interpreter检查到你有外面有装饰器@addspam的存在,这时候你就可以大致理解成解释器做了以下的手脚:
useful = addspam(useful)
很好的问题!
请搜索higher order functions了解更多信息。
因为我没有能力来清楚地解释,就放几篇我在学习函数式编程的时候看到的比较好的博文来帮助你理解。
函数式编程 | 酷 壳
Python修饰器的函数式编程
1.6 Higher-Order Functions
6. Functional Programming
我喜欢最后一篇文章,通过实例来理解效果更好。
Python中,函数并没有什么特殊的,就是一个对象。
你没理解修饰器。
用addspam修饰了useful后,你应该理解为这个函数变成了new。
当调用useful函数的时候,其实是调用了new。
没有复制,函数也是个对象,基本就和你 return 一个 list 一个 dict 没什么两样。
试试看在 Python REPL 中创建一个 function:
>>> def foobar(): print("你好") >>> foobar >>> func_list = [foobar, foobar, foobar] >>> func_list[0]()
不是简单地返回函数。至少在Python里,def定义的函数和lambda定义的函数,后者是包含closure的。
具体closure是什么,这真不是一句话能说清,我也不觉得我能说好,所以还是自己搜一下吧。
不要说我歧视用百度查这种问题,这去Google搜个nested functions多好。

Python is suitable for data science, web development and automation tasks, while C is suitable for system programming, game development and embedded systems. Python is known for its simplicity and powerful ecosystem, while C is known for its high performance and underlying control capabilities.

You can learn basic programming concepts and skills of Python within 2 hours. 1. Learn variables and data types, 2. Master control flow (conditional statements and loops), 3. Understand the definition and use of functions, 4. Quickly get started with Python programming through simple examples and code snippets.

Python is widely used in the fields of web development, data science, machine learning, automation and scripting. 1) In web development, Django and Flask frameworks simplify the development process. 2) In the fields of data science and machine learning, NumPy, Pandas, Scikit-learn and TensorFlow libraries provide strong support. 3) In terms of automation and scripting, Python is suitable for tasks such as automated testing and system management.

You can learn the basics of Python within two hours. 1. Learn variables and data types, 2. Master control structures such as if statements and loops, 3. Understand the definition and use of functions. These will help you start writing simple Python programs.

How to teach computer novice programming basics within 10 hours? If you only have 10 hours to teach computer novice some programming knowledge, what would you choose to teach...

How to avoid being detected when using FiddlerEverywhere for man-in-the-middle readings When you use FiddlerEverywhere...

Error loading Pickle file in Python 3.6 environment: ModuleNotFoundError:Nomodulenamed...

How to solve the problem of Jieba word segmentation in scenic spot comment analysis? When we are conducting scenic spot comments and analysis, we often use the jieba word segmentation tool to process the text...


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

SublimeText3 Mac version
God-level code editing software (SublimeText3)

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

SublimeText3 Chinese version
Chinese version, very easy to use

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

EditPlus Chinese cracked version
Small size, syntax highlighting, does not support code prompt function