# 编码规范

本文档定义新 SaaS 项目的 Python 编码规范。

---

## 1. 基础规范

遵循 [PEP 8](https://peps.python.org/pep-0008/)，以下是重点和补充。

### 1.1 命名规范

**模块/包**：小写 + 下划线
```python
# ✅ 正确
from packages.domain import entities
from packages.adapters.in_memory import project_repository

# ❌ 错误
from packages.Domain import Entities
from packages.adapters.InMemory import ProjectRepository
```

**类**：PascalCase
```python
# ✅ 正确
class Project:
    pass

class InMemoryProjectRepository:
    pass

# ❌ 错误
class project:
    pass

class in_memory_project_repository:
    pass
```

**函数/变量**：小写 + 下划线
```python
# ✅ 正确
def create_project(workspace_id: str, name: str) -> Project:
    pass

user_count = 10

# ❌ 错误
def CreateProject(workspace_id: str, name: str) -> Project:
    pass

UserCount = 10
```

**常量**：大写 + 下划线
```python
# ✅ 正确
MAX_PROJECT_NAME_LENGTH = 100
DEFAULT_PAGE_SIZE = 20

# ❌ 错误
maxProjectNameLength = 100
default_page_size = 20
```

**私有属性/方法**：前缀 `_`
```python
class Project:
    def __init__(self):
        self._internal_state = {}
    
    def _validate(self):
        pass
```

---

## 2. Type Hints

**强制使用** type hints，提升代码可读性和 IDE 支持。

```python
# ✅ 正确
def create_project(workspace_id: str, name: str, description: str = "") -> Project:
    pass

def list_projects(workspace_id: str) -> list[Project]:
    pass

def get_project(project_id: str) -> Project | None:
    pass

# ❌ 错误
def create_project(workspace_id, name, description=""):
    pass
```

**复杂类型**：
```python
from typing import Protocol, Any

# Dict/List
def update_metadata(metadata: dict[str, Any]) -> None:
    pass

# Optional (Python 3.10+ 用 | None)
def get_user(user_id: str) -> User | None:
    pass

# Protocol
class Repository(Protocol):
    def get(self, id: str) -> Entity | None:
        pass
```

---

## 3. Dataclass

**优先使用** `dataclass` 定义实体和值对象。

```python
from dataclasses import dataclass, field
from datetime import datetime, timezone

# ✅ 正确
@dataclass(slots=True)
class Project:
    id: str
    workspace_id: str
    name: str
    description: str = ""
    created_at: datetime = field(default_factory=lambda: datetime.now(timezone.utc))

# ❌ 错误（不用 dataclass）
class Project:
    def __init__(self, id: str, workspace_id: str, name: str, description: str = ""):
        self.id = id
        self.workspace_id = workspace_id
        self.name = name
        self.description = description
```

**为什么用 `slots=True`？**
- 节省内存
- 防止意外添加属性
- 提升性能

---

## 4. 注释与文档

### 4.1 模块/类/函数注释

**使用中文注释**。

```python
def create_project(workspace_id: str, name: str, description: str = "") -> Project:
    """
    创建项目。
    
    Args:
        workspace_id: 工作空间 ID
        name: 项目名称（不能为空）
        description: 项目描述（可选）
    
    Returns:
        创建的项目实体
    
    Raises:
        ValueError: 项目名称为空时
    """
    pass
```

### 4.2 复杂逻辑注释

```python
# 正确做法：复杂逻辑加注释
def calculate_priority(job: IngestJob) -> int:
    # 优先级规则：
    # 1. FAILED 状态最高（需要重试）
    # 2. PENDING 状态次高（等待处理）
    # 3. PROCESSING 状态最低（正在处理）
    if job.status == IngestJobStatus.FAILED:
        return 100
    elif job.status == IngestJobStatus.PENDING:
        return 50
    else:
        return 10
```

---

## 5. 异常处理

### 5.1 使用具体异常

```python
# ✅ 正确
def get_project(project_id: str) -> Project:
    if not project_id:
        raise ValueError("项目 ID 不能为空")
    
    project = repository.get(project_id)
    if project is None:
        raise KeyError(f"项目 {project_id} 不存在")
    
    return project

# ❌ 错误
def get_project(project_id: str) -> Project:
    if not project_id:
        raise Exception("错误")  # 太宽泛
```

### 5.2 自定义异常

```python
class ProjectNotFoundError(Exception):
    """项目不存在异常。"""
    pass

class ProjectNameTooLongError(ValueError):
    """项目名称过长异常。"""
    pass
```

---

## 6. Clean Architecture 约束

### 6.1 依赖方向

```
Apps (api/worker/web)
    ↓
Application (use cases)
    ↓
Ports (interfaces) ← Adapters (implementations)
    ↓
Domain (entities/rules)
```

**Domain 层**：
- ❌ 不能依赖任何外层
- ❌ 不能依赖 SQLAlchemy、FastAPI、Celery
- ✅ 只能依赖 Python 标准库

```python
# ✅ 正确（Domain 层）
from dataclasses import dataclass
from datetime import datetime
from uuid import uuid4

@dataclass(slots=True)
class Project:
    id: str
    name: str

# ❌ 错误（Domain 层）
from sqlalchemy import Column, String  # ❌ 不能依赖 SQLAlchemy
from fastapi import HTTPException  # ❌ 不能依赖 FastAPI

@dataclass(slots=True)
class Project:
    id: str
    name: str
```

**Application 层**：
- ✅ 可以依赖 Domain + Ports
- ❌ 不能依赖 Adapters

**Adapters 层**：
- ✅ 可以依赖 Domain + Ports
- ✅ 可以使用外部库（SQLAlchemy、Redis 等）

---

## 7. 测试

### 7.1 测试文件命名

```
tests/
├── integration/
│   ├── test_projects.py
│   ├── test_ingest_pipeline.py
│   └── test_classification_pipeline.py
└── unit/
    ├── test_project_entity.py
    └── test_asset_validation.py
```

### 7.2 测试函数命名

```python
# ✅ 正确
def test_create_project_with_valid_name():
    pass

def test_create_project_with_empty_name_should_fail():
    pass

def test_list_projects_by_workspace():
    pass

# ❌ 错误
def test1():
    pass

def test_project():
    pass
```

### 7.3 测试结构（AAA 模式）

```python
def test_create_project():
    # Arrange（准备）
    workspace_id = "ws-1"
    name = "测试项目"
    repository = InMemoryProjectRepository()
    use_case = CreateProjectUseCase(repository)
    
    # Act（执行）
    project = use_case.execute(
        CreateProjectCommand(workspace_id=workspace_id, name=name)
    )
    
    # Assert（断言）
    assert project.name == name
    assert project.workspace_id == workspace_id
```

---

## 8. 代码格式化

### 8.1 行长度

- 最大 120 字符
- 优先 88 字符（Black 默认）

### 8.2 导入顺序

```python
# 1. 标准库
import os
from datetime import datetime
from typing import Protocol

# 2. 第三方库
from fastapi import FastAPI
from sqlalchemy import Column

# 3. 本地模块
from packages.domain import Project
from packages.application import CreateProjectUseCase
```

### 8.3 空行

```python
# 类之间：2 行
class User:
    pass


class Workspace:
    pass


# 函数之间：1 行
def create_user():
    pass

def list_users():
    pass
```

---

## 9. 安全规范

### 9.1 禁止硬编码敏感信息

```python
# ❌ 错误
DATABASE_URL = "postgresql://admin:password123@localhost/db"
API_KEY = "sk-1234567890abcdef"

# ✅ 正确
import os
DATABASE_URL = os.getenv("DATABASE_URL")
API_KEY = os.getenv("API_KEY")
```

### 9.2 输入验证

```python
# ✅ 正确
def create_project(name: str) -> Project:
    clean_name = name.strip()
    if not clean_name:
        raise ValueError("项目名称不能为空")
    if len(clean_name) > 100:
        raise ValueError("项目名称不能超过 100 字符")
    
    return Project(id=uuid4().hex, name=clean_name)
```

---

## 10. 性能规范

### 10.1 避免 N+1 查询

```python
# ❌ 错误
projects = repository.list_by_workspace("ws-1")
for project in projects:
    assets = asset_repository.list_by_project(project.id)  # N+1

# ✅ 正确
projects = repository.list_by_workspace("ws-1")
project_ids = [p.id for p in projects]
assets = asset_repository.list_by_projects(project_ids)  # 一次查询
```

### 10.2 使用生成器

```python
# ✅ 正确（大数据集）
def list_all_assets() -> Generator[Asset, None, None]:
    for asset in repository.stream():
        yield asset

# ❌ 错误（加载全部到内存）
def list_all_assets() -> list[Asset]:
    return repository.list_all()  # 可能 OOM
```

---

**最后更新**: 2026-06-15  
**版本**: v1.0