（可选）在类方法上使用装饰器 [英] Optionally use decorators on class methods

问题描述

我是Python的新手，并且为API构建了包装器。我想让用户决定他/她是否想在我从我的模块公开的方法上使用装饰器。

Im new to Python, and im building a wrapper for an api. I would want to let the user decide if he/she wants to use a decorator on methods I expose from my module.

例如：

# create a new instance
api = MyApi()

# return a simple json response with all the data related to a timetable
print api.time_table

现在用户拥有所有数据，并且可以做他/她想要的一切。例如，我想添加某种便利方法；让用户获得json的一小部分而不是整个json大响应。

Now the user has all the data, and can do whatever he/she wants. I would want to add some kind of 'convenience' methods, for example; to let the user get a small part of the json instead of the whole big json response.

我的想法是为此使用python装饰器。可选地，我的目标可能是这样的：

My idea was to use pythons decorators for this. Optionally my goal whould be something like this:

# use the method and get al the data
print api.time_table

# Optionally, get a specific part, just the shows part. (PSEUDO CODE BELOW)
@shows
print api.time_table

那不是装饰器的工作方式，但是有没有办法在现有的类方法上选择性地使用装饰器，还是装饰器总是必须包装原始方法？

Naturally, thats not how decorators work, but is there a way to optionally use a decorator on a existing class method, or does the decorator always have to be wrapping the original method?

那么，这里最Python化的方式是什么？我真的很想使用装饰器，但是如果这不是一个好主意，那就在我的 Api 类中创建更多的便捷方法就可以了。

So what is the most Pythonic way here? I really would like to use decorator, but if thats a bad idea here, im fine with just creating more 'convenience' methods inside my Api class.

推荐答案

您的选择是向您的API添加更多方法或向用户提供实用功能：

Your options are to add more methods to your API or to provide the user with utility functions instead:

from yourmodule import MyAPI

api = MyAPI

filtered_timetable = api.filter_on(something)

或

from yourmodule import MyAPI, filter_timetable

api = MyAPI

filtered_timetable = filter_timetable(api.time_table, something)

记住装饰器只是可调用的；语法：

Remember that decorators are just callables; the syntax:

@foo
def bar():
    pass

只是以下方面的语法糖：

is just syntactic sugar for:

def bar():
    pass
bar = foo(bar)

foo（）被调用，并且返回值替换装饰的对象。通常，您将函数用作装饰器，但是没有什么说您必须仅将这些函数用作装饰器。

foo() is called, and the return value replaces the decorated object. Usually you use functions for decorators, but nothing says you have to use those functions only as decorators.

filter_timetable 可能是这样的装饰器；如果您有一个用例可同时使用。

filter_timetable could be such a decorator; if you have a usecase for using it as both.

这篇关于（可选）在类方法上使用装饰器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！