附录 A：Python 进阶速查

import asyncio

async def fetch_data():
    await asyncio.sleep(1)  # 模拟 IO（Input/Output，输入输出）等待
    return "data"

async def main():
    result = await fetch_data()
    print(result)

asyncio.run(main())

# 创建 dict 的两种写法
user = {"name": "Alice", "age": 30}
user = dict(name="Alice", age=30)

# 读写字段
print(user["name"])        # "Alice"
user["email"] = "[email protected]"  # 随意加字段
print(user["country"])     # KeyError! 访问不存在的键会崩溃

from typing import TypedDict

class User(TypedDict):
    name: str
    age: int

# 创建方式和普通 dict 完全一样
u: User = {"name": "Alice", "age": 30}  # OK
u = User(name="Alice", age=30)          # OK（TypedDict 特有写法）

# 运行时就是普通 dict
print(type(u))   # <class 'dict'>

# 类型检查器（mypy/pyright）会报错：
u = User(name="Alice", age="三十")  # ❌ age 应该是 int
u = User(name="Alice")             # ❌ 缺少 age（默认必填）
u = User(name="Alice", age=30, foo="bar")  # ❌ foo 不是合法字段
print(u["namee"])  # ❌ 拼写错误

from typing import TypedDict

class UserProfile(TypedDict, total=False):
    name: str
    age: int        # 现在 age 也是可选的
    bio: str        # 所有字段都是可选的

# total=False：所有字段都是可选的
u = UserProfile(name="Bob")          # OK，age 和 bio 可以不写
u = UserProfile()                     # OK，甚至全空也行

from typing import TypedDict, Required

class ToolUseBlock(TypedDict, total=False):
    id: Required[str]       # 必填（覆盖了 total=False）
    name: Required[str]     # 必填
    input: Required[dict]   # 必填
    raw_input: str | None   # 可选

# id、name、input 必填，raw_input 可选
block: ToolUseBlock = {"id": "1", "name": "search", "input": {"q": "hi"}}  # OK

block = ToolUseBlock(id="1", name="search", input={})  # OK
block = ToolUseBlock(id="1")                            # ❌ 缺少 name、input

from contextvars import ContextVar

user_id: ContextVar[str] = ContextVar("user_id", default="")

async def handle_request(name):
    user_id.set(name)
    await asyncio.sleep(0.1)
    print(f"{user_id.get()} processing")  # 不受其他任务影响

async def main():
    await asyncio.gather(
        handle_request("Alice"),
        handle_request("Bob"),
    )

class MyMeta(type):
    def __new__(mcs, name, bases, attrs):
        # 类定义时自动执行
        if "reply" in attrs:
            attrs["reply"] = wrap(attrs["reply"])
        return super().__new__(mcs, name, bases, attrs)

class Agent(metaclass=MyMeta):
    async def reply(self):  # 自动被 wrap 包装
        ...

from functools import wraps

def my_decorator(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        return func(*args, **kwargs)
    return wrapper

@my_decorator
def my_function():
    """My docstring"""
    pass

print(my_function.__name__)  # "my_function"（没有 @wraps 会是 "wrapper"）

async def stream_data():
    for i in range(3):
        await asyncio.sleep(0.1)
        yield i

async def main():
    async for value in stream_data():
        print(value)

asyncio.run(main())

from pydantic import BaseModel

class UserProfile(BaseModel):
    name: str
    age: int = 0

# 自动生成 JSON Schema
schema = UserProfile.model_json_schema()
# {"type": "object", "properties": {"name": {"type": "string"}, ...}}

# 自动验证
user = UserProfile(name="Alice", age=30)

import inspect

def greet(name: str, greeting: str = "Hello"):
    pass

sig = inspect.signature(greet)
for param_name, param in sig.parameters.items():
    print(f"{param_name}: {param.annotation}, default={param.default}")
# name: <class 'str'>, default=<Parameter.empty>
# greeting: <class 'str'>, default=Hello

from copy import deepcopy

original = {"msgs": [Msg("user", "hello", "user")]}
copied = deepcopy(original)  # 完全独立的副本

def handle_block(block: ContentBlock):
    match block:
        case {"type": "text", "text": str(t)}:
            return f"文本: {t}"
        case {"type": "tool_use", "name": str(n), "input": dict(i)}:
            return f"工具调用: {n}({i})"
        case {"type": "image"}:
            return "图片"
        case _:
            return "未知类型"