====== 第二十二章：虚拟环境与包管理 ======

===== 本章目标 =====

完成本章学习后，你将能够：
  * 创建和管理虚拟环境
  * 使用pip管理包
  * 理解依赖管理
  * 打包和发布Python项目

===== 虚拟环境 =====

==== venv模块 ====

<code bash>
# 创建虚拟环境
python -m venv myenv

# 激活
# Windows:
myenv\Scripts\activate

# macOS/Linux:
source myenv/bin/activate

# 退出
deactivate
</code>

==== conda环境 ====

<code bash>
# 创建环境
conda create -n myenv python=3.11

# 激活/退出
conda activate myenv
conda deactivate

# 删除环境
conda remove -n myenv --all
</code>

===== pip包管理 =====

<code bash>
# 安装
pip install package_name
pip install package==1.2.3
pip install package>=1.0,<2.0

# 从requirements安装
pip install -r requirements.txt

# 导出依赖
pip freeze > requirements.txt

# 卸载
pip uninstall package_name

# 列出已安装
pip list
pip list --outdated
</code>

===== requirements.txt =====

<code>
# 精确版本
requests==2.28.1
numpy==1.23.0

# 最低版本
flask>=2.0.0

# 版本范围
django>=3.0,<4.0

# 可选依赖
pytest>=6.0; extra == "test"
</code>

===== 打包与发布 =====

<code python>
# pyproject.toml
[build-system]
requires = ["setuptools>=45", "wheel"]
build-backend = "setuptools.build_meta"

[project]
name = "my_package"
version = "1.0.0"
description = "A sample package"
readme = "README.md"
requires-python = ">=3.8"
license = {text = "MIT"}
authors = [
    {name = "Your Name", email = "your@email.com"}
]
dependencies = [
    "requests>=2.0",
    "numpy>=1.20"
]

[project.optional-dependencies]
dev = ["pytest", "black", "flake8"]
</code>

===== 本章练习 =====

1. 创建并管理虚拟环境
2. 编写requirements.txt
3. 打包并发布到PyPI测试

下一章：[[python_course:chapter23|第二十三章：os与sys模块]]