Python 命名空间包

摘要：常规包是包含 __init__.py 文件的目录。此文件指示应将目录视为包。__init__.py 文件可以为空，但它通常用于初始化包、定义向外部公开的内容或在导入包时运行设置代码。

在 Python 中，用包来组织模块。

Python 包

两种类型的包：

常规包命名空间包

常规包是包含 __init__.py 文件的目录。此文件指示应将目录视为包。__init__.py 文件可以为空，但它通常用于初始化包、定义向外部公开的内容或在导入包时运行设置代码。

mypackage/ __init__.py module1.py module2.py

命名空间包是一种类似包的结构，不需要 __init__.py 文件，并且可以跨越多个目录。它允许分布式和灵活的包创建，从而可以将包的不同部分拆分到不同的位置。

想象一下分布在两个目录中的命名空间包 mynamespace：

目录 1：

project1/mynamespace/ module1.py

目录 2：

project2/mynamespace/ module2.py

用法

import mynamespace.module1import mynamespace.module2

Python 会将两个 mynamespace 目录合并到一个命名空间包中，使所有模块都可以访问。

我们了解到 Namespace 包的源代码可以分布在多个目录中。它有助于根据团队对大型项目进行解耦，以便可以独立开发和分发包的组件。

例如：一个存储库（一个团队）可以处理一个组件，另一个团队可以处理同一包的另一个组件，但独立开发和分发。

让我们了解 Namespace 包如何帮助独立开发和分发包。

假设我们有一个公司（log-corp）提供了一个大而有用的包。但是该包的子包/模块在不同的存储库（目录）中是多样化的，因为不同的团队正在处理它。

log_corp 是主包，其中包含许多跨团队开发并独立分发的子包和模块。版本控制和包分发将独立进行。他们唯一共享的是命名空间。（所有子包和模块都将归入主包log_corp）

使用 src 布局。

LOG_CORP_COMP1/├── src/│ └── log_corp/│ ├── sub_pkg1/│ │ └── sub_module1.py│ └── module1.py├── pyproject.toml└── README.md

module1.py

def func1: print('From log-corp module1')

sub_module1.py

def sub_func1: print('From log-corp submodule1')

pyproject.toml 文件

[build-system]requires = ["setuptools"]build-backend = "setuptools.build_meta"[project]name = "log-corp1" # as if it appears in pypiauthors = [ {name = "Logesh", email = "log@gmail.com"},]description = "My package description"readme = "README.md"requires-python = ">=3.10"license = {text = "MIT License"}classifiers = [ "Programming Language :: Python :: 3",]version = "1.0.1" # version 1.0.1构建软件包PS C:\Users\L\Desktop\log_corp_comp1> ls Directory: C:\Users\L\Desktop\log_corp_comp1Mode LastWriteTime Length Name---- ------ ----d----- 12/28/2024 11:32 AM src-a---- 12/28/2024 11:41 AM 387 pyproject.toml-a---- 12/28/2024 11:31 AM 34 README.mdPS C:\Users\L\Desktop\log_corp_comp1> python -m build* Creating isolated environment: venv+pip...* Installing packages in isolated environment: - setuptools* Getting build dependencies for sdist...running egg_infocreating src\log_corp1.egg-infowriting src\log_corp1.egg-info\PKG-INFOwriting dependency_links to src\log_corp1.egg-info\dependency_links.txtwriting top-level names to src\log_corp1.egg-info\top_level.txtwriting manifest file 'src\log_corp1.egg-info\SOURCES.txt'reading manifest file 'src\log_corp1.egg-info\SOURCES.txt'writing manifest file 'src\log_corp1.egg-info\SOURCES.txt'* Building sdist...running sdistrunning egg_infowriting src\log_corp1.egg-info\PKG-INFOwriting dependency_links to src\log_corp1.egg-info\dependency_links.txtwriting top-level names to src\log_corp1.egg-info\top_level.txtreading manifest file 'src\log_corp1.egg-info\SOURCES.txt'writing manifest file 'src\log_corp1.egg-info\SOURCES.txt'running checkcreating log_corp1-1.0.1creating log_corp1-1.0.1\src\log_corpcreating log_corp1-1.0.1\src\log_corp1.egg-infocreating log_corp1-1.0.1\src\log_corp\sub_pkg1copying files to log_corp1-1.0.1...copying README.md -> log_corp1-1.0.1copying pyproject.toml -> log_corp1-1.0.1copying src\log_corp\module1.py -> log_corp1-1.0.1\src\log_corpcopying src\log_corp1.egg-info\PKG-INFO -> log_corp1-1.0.1\src\log_corp1.egg-infocopying src\log_corp1.egg-info\SOURCES.txt -> log_corp1-1.0.1\src\log_corp1.egg-infocopying src\log_corp1.egg-info\dependency_links.txt -> log_corp1-1.0.1\src\log_corp1.egg-infocopying src\log_corp1.egg-info\top_level.txt -> log_corp1-1.0.1\src\log_corp1.egg-infocopying src\log_corp\sub_pkg1\sub_module1.py -> log_corp1-1.0.1\src\log_corp\sub_pkg1copying src\log_corp1.egg-info\SOURCES.txt -> log_corp1-1.0.1\src\log_corp1.egg-infoWriting log_corp1-1.0.1\setup.cfgCreating tar archiveremoving 'log_corp1-1.0.1' (and everything under it)* Building wheel from sdist* Creating isolated environment: venv+pip...* Installing packages in isolated environment: - setuptools* Getting build dependencies for wheel...running egg_infowriting src\log_corp1.egg-info\PKG-INFOwriting dependency_links to src\log_corp1.egg-info\dependency_links.txtwriting top-level names to src\log_corp1.egg-info\top_level.txtreading manifest file 'src\log_corp1.egg-info\SOURCES.txt'writing manifest file 'src\log_corp1.egg-info\SOURCES.txt'* Building wheel...running bdist_wheelrunning buildrunning build_pycreating build\lib\log_corpcopying src\log_corp\module1.py -> build\lib\log_corpcreating build\lib\log_corp\sub_pkg1copying src\log_corp\sub_pkg1\sub_module1.py -> build\lib\log_corp\sub_pkg1running egg_infowriting src\log_corp1.egg-info\PKG-INFOwriting dependency_links to src\log_corp1.egg-info\dependency_links.txtwriting top-level names to src\log_corp1.egg-info\top_level.txtreading manifest file 'src\log_corp1.egg-info\SOURCES.txt'writing manifest file 'src\log_corp1.egg-info\SOURCES.txt'installing to build\bdist.win-amd64\wheelrunning installrunning install_libcreating build\bdist.win-amd64\wheelcreating build\bdist.win-amd64\wheel\log_corpcopying build\lib\log_corp\module1.py -> build\bdist.win-amd64\wheel\.\log_corpcreating build\bdist.win-amd64\wheel\log_corp\sub_pkg1copying build\lib\log_corp\sub_pkg1\sub_module1.py -> build\bdist.win-amd64\wheel\.\log_corp\sub_pkg1running install_egg_infoCopying src\log_corp1.egg-info to build\bdist.win-amd64\wheel\.\log_corp1-1.0.1-py3.11.egg-inforunning install_scriptscreating build\bdist.win-amd64\wheel\log_corp1-1.0.1.dist-info\WHEELcreating 'C:\Users\L\Desktop\log_corp_comp1\dist\.tmp-ryh5ya6f\log_corp1-1.0.1-py3-none-any.whl' and adding 'build\bdist.win-amd64\wheel' to itadding 'log_corp/module1.py'adding 'log_corp/sub_pkg1/sub_module1.py'adding 'log_corp1-1.0.1.dist-info/METADATA'adding 'log_corp1-1.0.1.dist-info/WHEEL'adding 'log_corp1-1.0.1.dist-info/top_level.txt'adding 'log_corp1-1.0.1.dist-info/RECORD'removing build\bdist.win-amd64\wheelSuccessfully built log_corp1-1.0.1.tar.gz and log_corp1-1.0.1-py3-none-any.whlPS C:\Users\L\Desktop\log_corp_comp1>团队 2（存储库 2）

src 布局

LOG_CORP_COMP2/├── src/│ └── log_corp/│ ├── sub_pkg2/│ │ └── sub_module2.py│ └── module2.py├── pyproject.toml└── README.md

module2.py

def func2: print('From log-corp module2')

sub_module2.py

def sub_func2: print('From log-corp submodule2')[build-system]requires = ["setuptools"]build-backend = "setuptools.build_meta"[project]name = "log-corp2" # Different package name from the previous oneauthors = [ {name = "Logesh", email = "log@gmail.com"},]description = "My package description"readme = "README.md"requires-python = ">=3.10"license = {text = "MIT License"}classifiers = [ "Programming Language :: Python :: 3",]version = "1.0.2" # Different version 构建了软件包PS E:\Documents\log_corp_comp2> ls Directory: E:\Documents\log_corp_comp2Mode LastWriteTime Length Name---- ------ ----d----- 12/28/2024 11:25 AM src-a---- 12/28/2024 11:31 AM 34 README.md-a---- 12/28/2024 11:41 AM 387 pyproject.tomlPS E:\Documents\log_corp_comp2> python -m build* Creating isolated environment: venv+pip...* Installing packages in isolated environment: - setuptools* Getting build dependencies for sdist...running egg_infocreating src\log_corp2.egg-infowriting src\log_corp2.egg-info\PKG-INFOwriting dependency_links to src\log_corp2.egg-info\dependency_links.txtwriting top-level names to src\log_corp2.egg-info\top_level.txtwriting manifest file 'src\log_corp2.egg-info\SOURCES.txt'reading manifest file 'src\log_corp2.egg-info\SOURCES.txt'writing manifest file 'src\log_corp2.egg-info\SOURCES.txt'* Building sdist...running sdistrunning egg_infowriting src\log_corp2.egg-info\PKG-INFOwriting dependency_links to src\log_corp2.egg-info\dependency_links.txtwriting top-level names to src\log_corp2.egg-info\top_level.txtreading manifest file 'src\log_corp2.egg-info\SOURCES.txt'writing manifest file 'src\log_corp2.egg-info\SOURCES.txt'running checkcreating log_corp2-1.0.2creating log_corp2-1.0.2\src\log_corpcreating log_corp2-1.0.2\src\log_corp2.egg-infocreating log_corp2-1.0.2\src\log_corp\sub_pkg2copying files to log_corp2-1.0.2...copying README.md -> log_corp2-1.0.2copying pyproject.toml -> log_corp2-1.0.2copying src\log_corp\module2.py -> log_corp2-1.0.2\src\log_corpcopying src\log_corp2.egg-info\PKG-INFO -> log_corp2-1.0.2\src\log_corp2.egg-infocopying src\log_corp2.egg-info\SOURCES.txt -> log_corp2-1.0.2\src\log_corp2.egg-infocopying src\log_corp2.egg-info\dependency_links.txt -> log_corp2-1.0.2\src\log_corp2.egg-infocopying src\log_corp2.egg-info\top_level.txt -> log_corp2-1.0.2\src\log_corp2.egg-infocopying src\log_corp\sub_pkg2\sub_module2.py -> log_corp2-1.0.2\src\log_corp\sub_pkg2Writing log_corp2-1.0.2\setup.cfgCreating tar archiveremoving 'log_corp2-1.0.2' (and everything under it)* Building wheel from sdist* Creating isolated environment: venv+pip...* Installing packages in isolated environment: - setuptools* Getting build dependencies for wheel...running egg_infowriting src\log_corp2.egg-info\PKG-INFOwriting dependency_links to src\log_corp2.egg-info\dependency_links.txtwriting top-level names to src\log_corp2.egg-info\top_level.txtreading manifest file 'src\log_corp2.egg-info\SOURCES.txt'writing manifest file 'src\log_corp2.egg-info\SOURCES.txt'* Building wheel...running bdist_wheelrunning buildrunning build_pycreating build\lib\log_corpcopying src\log_corp\module2.py -> build\lib\log_corpcreating build\lib\log_corp\sub_pkg2copying src\log_corp\sub_pkg2\sub_module2.py -> build\lib\log_corp\sub_pkg2running egg_infowriting src\log_corp2.egg-info\PKG-INFOwriting dependency_links to src\log_corp2.egg-info\dependency_links.txtwriting top-level names to src\log_corp2.egg-info\top_level.txtreading manifest file 'src\log_corp2.egg-info\SOURCES.txt'writing manifest file 'src\log_corp2.egg-info\SOURCES.txt'installing to build\bdist.win-amd64\wheelrunning installrunning install_libcreating build\bdist.win-amd64\wheelcreating build\bdist.win-amd64\wheel\log_corpcopying build\lib\log_corp\module2.py -> build\bdist.win-amd64\wheel\.\log_corpcreating build\bdist.win-amd64\wheel\log_corp\sub_pkg2copying build\lib\log_corp\sub_pkg2\sub_module2.py -> build\bdist.win-amd64\wheel\.\log_corp\sub_pkg2running install_egg_infoCopying src\log_corp2.egg-info to build\bdist.win-amd64\wheel\.\log_corp2-1.0.2-py3.11.egg-inforunning install_scriptscreating build\bdist.win-amd64\wheel\log_corp2-1.0.2.dist-info\WHEELcreating 'E:\Documents\log_corp_comp2\dist\.tmp-bn0t41tx\log_corp2-1.0.2-py3-none-any.whl' and adding 'build\bdist.win-amd64\wheel' to itadding 'log_corp/module2.py'adding 'log_corp/sub_pkg2/sub_module2.py'adding 'log_corp2-1.0.2.dist-info/METADATA'adding 'log_corp2-1.0.2.dist-info/WHEEL'adding 'log_corp2-1.0.2.dist-info/top_level.txt'adding 'log_corp2-1.0.2.dist-info/RECORD'removing build\bdist.win-amd64\wheelSuccessfully built log_corp2-1.0.2.tar.gz and log_corp2-1.0.2-py3-none-any.whlPS E:\Documents\log_corp_comp2>

创建虚拟环境。

因此，我们安装了 2 个共享相同命名空间的不同包（主包）。所以，现在这两个软件包 log_corp1 和 log_corp2 可以独立进行开发、分发、安装、升级、版本化。（仍然共享相同的命名空间，即所谓的 Namespace 包。

在这里，源的合并是在安装过程中自动完成的，并且在合并过程中没有冲突。这是使用 Namespace 包的主要好处之一。

将 log-corp 作为一个整体使用，它是从不同来源安装的。

一个明显的缺点是 import * 到 log_corp 无法按预期工作。

由于没有__init__.py文件来初始化包。

为两个组件添加 __init__.py，并在该文件中进行一些初始化。

组件 1LOG_CORP_COMP1/├── src/│ └── log_corp/│ ├── sub_pkg1/│ │ ├── __init__.py│ │ └── sub_module1.py│ ├── __init__.py│ └── module1.py├── pyproject.toml└── README.md

log_corp/__init__.py

from . import module1from . import sub_pkg1

log_corp/sub_pkg1/__init__.py

from . import sub_module1

其余文件具有相同的内容。

组件 2LOG_CORP_COMP2/├── src/│ └── log_corp/│ ├── sub_pkg2/│ │ ├── __init__.py│ │ └── sub_module2.py│ ├── __init__.py│ └── module2.py├── pyproject.toml└── README.mdfrom . import module2from . import sub_pkg2

log_corp/sub_pkg2/__init__.py

from . import sub_module2

其余文件具有相同的内容。

构建两个软件包组件 1PS C:\Users\L\Desktop\log_corp_comp1> python -m build* Creating isolated environment: venv+pip...* Installing packages in isolated environment: - setuptools* Getting build dependencies for sdist...running egg_infocreating src\log_corp1.egg-inforemoving build\bdist.win-amd64\wheelSuccessfully built log_corp1-1.0.1.tar.gz and log_corp1-1.0.1-py3-none-any.whlPS C:\Users\L\Desktop\log_corp_comp1>PS C:\Users\L\Desktop\log_corp_comp1> ls Directory: C:\Users\L\Desktop\log_corp_comp1Mode LastWriteTime Length Name---- ------ ----d----- 12/28/2024 1:31 PM distd----- 12/28/2024 1:31 PM src-a---- 12/28/2024 11:41 AM 387 pyproject.toml-a---- 12/28/2024 11:31 AM 34 README.mdPS C:\Users\L\Desktop\log_corp_comp1>组件 2PS E:\Documents\log_corp_comp2> python -m build* Creating isolated environment: venv+pip...* Installing packages in isolated environment: - setuptools* Getting build dependencies for sdist...running egg_infocreating src\log_corp2.egg-infowriting src\log_corp2.egg-info\PKG-INFOwriting dependency_links to src\log_corp2.egg-info\dependency_links.txtwriting top-level names to src\log_corp2.egg-info\top_level.txtwriting manifest file 'src\log_corp2.egg-info\SOURCES.txt'reading manifest file 'src\log_corp2.egg-info\SOURCES.txt'writing manifest file 'src\log_corp2.egg-info\SOURCES.txt'* Building sdist...running sdistrunning egg_infoWriting log_corp2-1.0.2\setup.cfgCreating tar archiveremoving 'log_corp2-1.0.2' (and everything under it)* Building wheel from sdist* Creating isolated environment: venv+pip...* Installing packages in isolated environment: - setuptools* Getting build dependencies for wheel...running egg_infoSuccessfully built log_corp2-1.0.2.tar.gz and log_corp2-1.0.2-py3-none-any.whlPS E:\Documents\log_corp_comp2>用法

已卸载之前安装的软件包。

安装软件包 log_corp1

在脚本中使用它。

module1 和 subpkg1 是可访问的

安装软件包 log_corp2

此安装会直接覆盖 log_corp/__init__.py 文件。

现在只有 log_corp2 的模块和子包可用。

但是我们仍然可以从 log_corp1 访问包/模块，将 log_corp 作为主包。

唯一需要注意的是，log_corp/__init__.py 被 log_corp2 覆盖。因此，如果我们有任何来自 log_corp1 的关键初始化将受到影响，这可能会导致包损坏问题。

结论

命名空间包是创建灵活且可扩展的 Python 包的现代方法。它们允许包的多个部分驻留在不同的目录中或分布在多个项目中。这使它们成为大型项目、插件系统或独立开发组件的情况的理想选择。

导入时的行为*无__init__.py功能：如果没有 __init__.py 文件，您将无法初始化包、定义默认导入或设置包级逻辑。通配符导入的复杂性：不支持 import *，在某些用例中可能会带来不便。运行时组合：解析完整的包结构在运行时进行，如果目录配置错误，可能会导致细微的问题。调试挑战：由于软件包的各个部分分布在多个位置，因此调试和跟踪问题可能会更加困难。

将命名空间包用于分布式模块化系统或框架。对于更简单的项目或需要与较旧的 Python 版本兼容时，请坚持使用常规包。