問題描述

我的包有以下結構:

mobilescouter/
    __init__.py #1
    mapper/
        __init__.py  #2
        lxml/
            __init__.py #3
            vehiclemapper.py
            vehiclefeaturemapper.py
            vehiclefeaturesetmapper.py
        ...
        basemapper.py
   vehicle/
        __init__.py #4
        vehicle.py
        vehiclefeature.py
        vehiclefeaturemapper.py
   ...

我不確定應該如何正確編寫 __init__.py 文件.
__init__.py #1 看起來像:

I'm not sure how the __init__.py files should be correctly written.
The __init__.py #1 looks like:

__all__ = ['mapper', 'vehicle']
import mapper
import vehicle

但是例如 __init__.py #2 應該是什么樣子?我的是:

But how should for example __init__.py #2 look like? Mine is:

__all__ = ['basemapper', 'lxml']
from basemaper import *
import lxml

什么時候應該使用 __all__?

推薦答案

__all__ 非常好 - 它有助于指導導入語句而不自動導入模塊http://docs.python.org/tutorial/modules.html#importing-from-a-package

__all__ is very good - it helps guide import statements without automatically importing modules http://docs.python.org/tutorial/modules.html#importing-from-a-package

使用 __all__ 和 import * 是多余的，只需要 __all__

using __all__ and import * is redundant, only __all__ is needed

我認為在 __init__.py 中使用 import * 來導入包的最有力的原因之一是能夠重構已經成長為多個的腳本在不破壞現有應用程序的情況下編寫腳本.但是如果你從一開始就設計一個包.我認為最好將 __init__.py 文件留空.

I think one of the most powerful reasons to use import * in an __init__.py to import packages is to be able to refactor a script that has grown into multiple scripts without breaking an existing application. But if you're designing a package from the start. I think it's best to leave __init__.py files empty.

例如:

foo.py - contains classes related to foo such as fooFactory, tallFoo, shortFoo

然后應用程序增長，現在它是一個完整的文件夾

then the app grows and now it's a whole folder

foo/
    __init__.py
    foofactories.py
    tallFoos.py
    shortfoos.py
    mediumfoos.py
    santaslittlehelperfoo.py
    superawsomefoo.py
    anotherfoo.py

那么初始化腳本可以說

__all__ = ['foofactories', 'tallFoos', 'shortfoos', 'medumfoos',
           'santaslittlehelperfoo', 'superawsomefoo', 'anotherfoo']
# deprecated to keep older scripts who import this from breaking
from foo.foofactories import fooFactory
from foo.tallfoos import tallFoo
from foo.shortfoos import shortFoo

以便為執行以下操作而編寫的腳本在更改期間不會中斷:

so that a script written to do the following does not break during the change:

from foo import fooFactory, tallFoo, shortFoo

這篇關于如何編寫好的/正確的包 __init__.py 文件的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！