python 元编程

发布于 2024-08-25 16:24:29 字数 1080 浏览 5 评论 0原文

我正在尝试归档一项任务，结果发现该任务有点复杂，因为我不太擅长 Python 元编程。

我想要一个带有函数 get_location(name) 的模块 locations ，它返回在文件中的文件夹locations/中定义的类，并将名称传递给函数。类的名称类似于 NameLocation。

所以，我的文件夹结构：

program.py
locations/
    __init__.py
    first.py
    second.py

program.py将是smth with：

from locations import get_location
location = get_location('first')

并且位置是在first.py smth中定义的类，如下所示：

from locations import Location # base class for all locations, defined in __init__ (?)
class FirstLocation(Location):
    pass

等等。

好吧，我已经尝试了很多导入和getattribute 语句，但现在我感到无聊并投降。如何归档此类行为？

我不知道为什么，但是这段代码

def get_location(name):
   module = __import__(__name__ + '.' + name)
   #return getattr(module, titlecase(name) + 'Location')
   return module

返回了

>>> locations.get_location( 'first')
<module 'locations' from 'locations/__init__.py'>

位置模块！为什么？！

原文

I'm trying to archive a task which turns out to be a bit complicated since I'm not very good at Python metaprogramming.

I want to have a module locations with function get_location(name), which returns a class defined in a folder locations/ in the file with the name passed to function. Name of a class is something like NameLocation.

So, my folder structure:

program.py
locations/
    __init__.py
    first.py
    second.py

program.py will be smth with with:

from locations import get_location
location = get_location('first')

and the location is a class defined in first.py smth like this:

from locations import Location # base class for all locations, defined in __init__ (?)
class FirstLocation(Location):
    pass

etc.

Okay, I've tried a lot of import and getattribute statements but now I'm bored and surrender. How to archive such behaviour?

I don't know why, but this code

def get_location(name):
   module = __import__(__name__ + '.' + name)
   #return getattr(module, titlecase(name) + 'Location')
   return module

returns

>>> locations.get_location( 'first')
<module 'locations' from 'locations/__init__.py'>

the locations module! why?!

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

柒七 2024-09-01 16:24:29

您确实需要 __import__ 该模块；之后，从中获取 attr 并不难。

import sys

def get_location(name):
    fullpath = 'locations.' + name
    package = __import__(fullpath)
    module = sys.modules[fullpath]
    return getattr(module, name.title() + 'Location')

编辑：__import__返回包，所以还需要一个getattr，参见文档（并仔细阅读所有部分 - “按我说的做，而不是照我做的做”；-）。

You do need to __import__ the module; after that, getting an attr from it is not hard.

import sys

def get_location(name):
    fullpath = 'locations.' + name
    package = __import__(fullpath)
    module = sys.modules[fullpath]
    return getattr(module, name.title() + 'Location')

Edit: __import__ returns the package, so you need one more getattr, see the docs (and read all the section carefully -- "do as I say not as I do";-).

回复收藏 0 原文