在python web开发中的装饰器与类 [英] Decorators vs. classes in python web development

问题描述

我注意到Python Web框架处理请求处理的三个主要方式：装饰器，具有单个请求的方法的控制器类，以及使用GET / POST方法的请求类。

我很好奇这三种方法的美德。这些方法中有哪些主要优点或缺点？要解决想法，这里有三个例子。

Bottle < a>使用装饰器：

  @route（'/'）
 def index（）：
 return 'Hello World！'
  

>塔架使用控制器类：

  class HelloController （BaseController）：
 def index（self）：
 return'Hello World'
  

龙卷风使用请求处理程序类，其类型为：

pre> class MainHandler（tornado.web.RequestHandler）：
def get（self）：
self.write（Hello，world）


哪种风格是最佳做法？

解决方案

实际上有一个理由您列出的三种方法，具体针对每个项目。

• 瓶尝试将东西保持为
  尽可能简单/直接
  为程序员。使用装饰器
  为路线，您不必担心
  关于开发人员了解OOP。


• 支柱开发目标是使
  代码重新使用并且容易地
  与WSGI风格的HTTP
  流程路由集成。因此，他们有
  选择了一种组织
  路由的非常OOP方式。举个例子，你可以
  copy&将HelloController粘贴到任何
  Pylons应用程序，它应该只是
  神奇地工作。即使所述应用程序是
  ，通过WSGI以一些
  复杂的方式提供。


• 龙卷风还有另一个原因是
  以这样的方式做事情：
  龙卷风的基于epoll的IOLoop（与tornado.web.Application一起使用）
  将每个RequestHandler实例化为
  请求进来。通过将每个
  RequestHandler限制为一个特定的
  GET或POST这允许IOLoop到
  快速实例化类，
  处理请求，最后让
  得到垃圾回收。不管
  的许多RequestHandler你的应用程序
  有多少，这样可以使
  快速而高效。这也是为什么龙卷风可以处理比其他基于Python的Web服务器更多的同时请求的原因（每个请求都获得自己的实例）。

现在，已经说了一切，你应该知道，你可以总是覆盖默认的框架行为。例如，我写了一个 MethodDispatcher ，它使得它更像Pylons（好吧，当我写了CherryPy时）。由于有一个大的RequestHandler（而不是很多小的），它会减轻龙卷风的微量（并增加内存占用），但是它可以减少应用程序中的代码量，使其更容易阅读（在我偏见中，当然=）。

I've noticed three main ways Python web frameworks deal request handing: decorators, controller classes with methods for individual requests, and request classes with methods for GET/POST.

I'm curious about the virtues of these three approaches. Are there major advantages or disadvantages to any of these approaches? To fix ideas, here are three examples.

Bottle uses decorators:

@route('/')
def index():
    return 'Hello World!'

Pylons uses controller classes:

class HelloController(BaseController):
    def index(self):
        return 'Hello World'

Tornado uses request handler classes with methods for types:

 class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.write("Hello, world")

Which style is the best practice?

解决方案

There's actually a reason for each of the three methods you listed, specific to each project.

• Bottle tries to keep things as simple/straightforward as possible for the programmer. With decorators for routes you don't have to worry about the developer understanding OOP.
• Pylons development goal is to make code re-usable and to be easily integrated with WSGI-style HTTP process routing. As such, they have chosen a very OOP way of organizing routes. As an example, you could copy & paste HelloController into any Pylons app and it should just magically work. Even if said app is being served up via WSGI in some complicated fashion.
• Tornado has yet another reason for doing things the way it does: Tornado's epoll-based IOLoop (in conjunction with tornado.web.Application) instantiates each RequestHandler as requests come in. By keeping each RequestHandler limited to a specific GET or POST this allows IOLoop to quickly instantiate the class, process the request, and finally let it get garbage collected. This keeps it fast and efficient with a small memory footprint regardless of how many RequestHandlers your application has. This is also the reason why Tornado can handle so many more simultaneous requests than other Python-based web servers (each request gets its own instance).

Now, having said all that you should know that you can always override the default framework behavior. For example, I wrote a MethodDispatcher for Tornado that makes it work more like Pylons (well, I had CherryPy in mind when I wrote it). It slows down Tornado a tiny amount (and increases the memory footprint slightly) due to having one large RequestHandler (as opposed to a lot of small ones) but it can reduce the amount of code in your app and make it a little easier to read (In my biased opinion, of course =).

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