项目地址： https://git.io/pytips
Python 的修饰器是一种语法糖（Syntactic Sugar），也就是说：
@decorator@wrapdef func(): pass
是下面语法的一种简写：
def func(): passfunc = decorator(wrap(func))
关于修饰器的两个主要问题：
-
修饰器用来修饰谁
-
谁可以作为修饰器
修饰函数
修饰器最常见的用法是修饰新定义的函数，在 0x0d 上下文管理器 中提到上下文管理器主要是为了 更优雅地完成善后工作 ，而修饰器通常用于扩展函数的行为或属性：
def log(func): def wraper(): print("INFO: Starting {}".format(func.__name__)) func() print("INFO: Finishing {}".format(func.__name__)) return wraper@logdef run(): print("Running run...")run() INFO: Starting runRunning run...INFO: Finishing run
修饰类
除了修饰函数之外，Python 3.0 之后增加了对新定义类的修饰（ PEP 3129 ），但是对于类别属性的修改可以通过 Metaclasses 或继承来实现，而新增加的类别修饰器更多是出于 Jython 以及 IronPython 的考虑，但其语法还是很一致的：
from time import sleep, timedef timer(Cls): def wraper(): s = time() obj = Cls() e = time() print("Cost {:.3f}s to init.".format(e - s)) return obj return wraper@timerclass Obj: def __init__(self): print("Hello") sleep(3) print("Obj")o = Obj() HelloObjCost 3.005s to init.
类作为修饰器
上面两个例子都是以函数作为修饰器，因为函数才可以被调用（callable） decorator(wrap(func)) 。除了函数之外，我们也可以定义可被调用的类，只要添加 __call__ 方法即可：
class HTML(object): """ Baking HTML Tags! """ def __init__(self, tag="p"): print("LOG: Baking Tag <{}>!".format(tag)) self.tag = tag def __call__(self, func): return lambda: "<{0}>{1}</{0}>".format(self.tag, func(), self.tag)@HTML("html")@HTML("body")@HTML("div")def body(): return "Hello"print(body()) LOG: Baking Tag <html>!LOG: Baking Tag <body>!LOG: Baking Tag <div>!<html><body><div>Hello</div></body></html>
传递参数
在实际使用过程中，我们可能需要向修饰器传递参数，也有可能需要向被修饰的函数（或类）传递参数。按照语法约定，只要修饰器 @decorator 中的 decorator 是可调用即可， decorator(123) 如果返回一个新的可调用函数，那么也是合理的，上面的 @HTML('html') 即是一例，下面再以 flask 的路由修饰器为例说明如何传递参数给修饰器：
RULES = {}def route(rule): def decorator(hand): RULES.update({rule: hand}) return hand return decorator@route("/")def index(): print("Hello world!")def home(): print("Welcome Home!")home = route("/home")(home)index()home()print(RULES) Hello world!Welcome Home!{'/': <function index at 0x10706f730>, '/home': <function home at 0x10706f8c8>} 向被修饰的函数传递参数，要看我们的修饰器是如何作用的，如果像上面这个例子一样未执行被修饰函数只是将其原模原样地返回，则不需要任何处理（这就把函数当做普通的值一样看待即可）：
@route("/login")def login(user = "user", pwd = "pwd"): print("DB.findOne({{{}, {}}})".format(user, pwd))login("hail", "python") DB.findOne({hail, python}) 如果需要在修饰器内执行，则需要稍微变动一下：
def log(f): def wraper(*args, **kargs): print("INFO: Start Logging") f(*args, **kargs) print("INFO: Finish Logging") return wraper@logdef run(hello = "world"): print("Hello {}".format(hello))run("Python") INFO: Start LoggingHello PythonINFO: Finish Logging
functools
由于修饰器将函数（或类）进行包装之后重新返回： func = decorator(func) ，那么有可能改变原本函数（或类）的一些信息，以上面的 HTML 修饰器为例：
@HTML("body")def body(): """ return body content """ return "Hello, body!"print(body.__name__)print(body.__doc__) LOG: Baking Tag <body>!<lambda>None
因为 body = HTML("body")(body) ，而 HTML("body").__call__() 返回的是一个 lambda 函数，因此 body 已经被替换成了 lambda ，虽然都是可执行的函数，但原来定义的 body 中的一些属性，例如 __doc__ / __name__ / __module__ 都被替换了（在本例中 __module__ 没变因为都在同一个文件中）。为了解决这一问题 Python 提供了 functools 标准库，其中包括了 update_wrapper 和 wraps 两个方法（ 源码 ）。其中 update_wrapper 就是用来将原来函数的信息赋值给修饰器中返回的函数：
from functools import update_wrapper"""functools.update_wrapper(wrapper, wrapped[, assigned][, updated])"""class HTML(object): """ Baking HTML Tags! """ def __init__(self, tag="p"): print("LOG: Baking Tag <{}>!".format(tag)) self.tag = tag def __call__(self, func): wraper = lambda: "<{0}>{1}</{0}>".format(self.tag, func(), self.tag) update_wrapper(wraper, func) return wraper@HTML("body")def body(): """ return body content! """ return "Hello, body!"print(body.__name__)print(body.__doc__) LOG: Baking Tag <body>!body return body content!
有趣的是 update_wrapper 的用法本身就很像是修饰器，因此 functools.wraps 就利用 functools.partial （还记得函数式编程中的偏应用吧！）将其变成一个修饰器：
from functools import update_wrapper, partialdef my_wraps(wrapped): return partial(update_wrapper, wrapped=wrapped)def log(func): @my_wraps(func) def wraper(): print("INFO: Starting {}".format(func.__name__)) func() print("INFO: Finishing {}".format(func.__name__)) return wraper@logdef run(): """ Docs' of run """ print("Running run...")print(run.__name__)print(run.__doc__) run Docs' of run
欢迎关注公众号 PyHub！
参考
-
Python修饰器的函数式编程
HTML as a Markup Language: Its Function and PurposeApr 22, 2025 am 12:02 AMThe function of HTML is to define the structure and content of a web page, and its purpose is to provide a standardized way to display information. 1) HTML organizes various parts of the web page through tags and attributes, such as titles and paragraphs. 2) It supports the separation of content and performance and improves maintenance efficiency. 3) HTML is extensible, allowing custom tags to enhance SEO.
The Future of HTML, CSS, and JavaScript: Web Development TrendsApr 19, 2025 am 12:02 AMThe future trends of HTML are semantics and web components, the future trends of CSS are CSS-in-JS and CSSHoudini, and the future trends of JavaScript are WebAssembly and Serverless. 1. HTML semantics improve accessibility and SEO effects, and Web components improve development efficiency, but attention should be paid to browser compatibility. 2. CSS-in-JS enhances style management flexibility but may increase file size. CSSHoudini allows direct operation of CSS rendering. 3.WebAssembly optimizes browser application performance but has a steep learning curve, and Serverless simplifies development but requires optimization of cold start problems.
HTML: The Structure, CSS: The Style, JavaScript: The BehaviorApr 18, 2025 am 12:09 AMThe roles of HTML, CSS and JavaScript in web development are: 1. HTML defines the web page structure, 2. CSS controls the web page style, and 3. JavaScript adds dynamic behavior. Together, they build the framework, aesthetics and interactivity of modern websites.
The Future of HTML: Evolution and Trends in Web DesignApr 17, 2025 am 12:12 AMThe future of HTML is full of infinite possibilities. 1) New features and standards will include more semantic tags and the popularity of WebComponents. 2) The web design trend will continue to develop towards responsive and accessible design. 3) Performance optimization will improve the user experience through responsive image loading and lazy loading technologies.
HTML vs. CSS vs. JavaScript: A Comparative OverviewApr 16, 2025 am 12:04 AMThe roles of HTML, CSS and JavaScript in web development are: HTML is responsible for content structure, CSS is responsible for style, and JavaScript is responsible for dynamic behavior. 1. HTML defines the web page structure and content through tags to ensure semantics. 2. CSS controls the web page style through selectors and attributes to make it beautiful and easy to read. 3. JavaScript controls web page behavior through scripts to achieve dynamic and interactive functions.
HTML: Is It a Programming Language or Something Else?Apr 15, 2025 am 12:13 AMHTMLisnotaprogramminglanguage;itisamarkuplanguage.1)HTMLstructuresandformatswebcontentusingtags.2)ItworkswithCSSforstylingandJavaScriptforinteractivity,enhancingwebdevelopment.
HTML: Building the Structure of Web PagesApr 14, 2025 am 12:14 AMHTML is the cornerstone of building web page structure. 1. HTML defines the content structure and semantics, and uses, etc. tags. 2. Provide semantic markers, such as, etc., to improve SEO effect. 3. To realize user interaction through tags, pay attention to form verification. 4. Use advanced elements such as, combined with JavaScript to achieve dynamic effects. 5. Common errors include unclosed labels and unquoted attribute values, and verification tools are required. 6. Optimization strategies include reducing HTTP requests, compressing HTML, using semantic tags, etc.
From Text to Websites: The Power of HTMLApr 13, 2025 am 12:07 AMHTML is a language used to build web pages, defining web page structure and content through tags and attributes. 1) HTML organizes document structure through tags, such as,. 2) The browser parses HTML to build the DOM and renders the web page. 3) New features of HTML5, such as, enhance multimedia functions. 4) Common errors include unclosed labels and unquoted attribute values. 5) Optimization suggestions include using semantic tags and reducing file size.
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
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
SecLists
SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.
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
SAP NetWeaver Server Adapter for Eclipse
Integrate Eclipse with SAP NetWeaver application server.
MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.
Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.
