x = x + 1  # 边界补偿 (OK)

def count_score():
    # 计算用户活跃度得分：
    # - 登录次数 × 0.3
    # - 发帖数 × 0.5
    # - 点赞数 × 0.2
    score = logins * 0.3 + posts * 0.5 + likes * 0.2
    return score

def add(a, b):
    """Return the sum of a and b."""
    return a + b

def calculate_score(logins: int, posts: int) -> float:
    """计算用户活跃度得分。

    使用加权公式：logins * 0.3 + posts * 0.5

    Args:
        logins (int): 用户登录次数
        posts (int): 用户发帖数量

    Returns:
        float: 活跃度得分，范围 [0, ∞)

    Raises:
        ValueError: 如果输入为负数
    """
    if logins < 0 or posts < 0:
        raise ValueError("输入值不能为负")
    return logins * 0.3 + posts * 0.5

# 好的实践
sum = 1 + 1
# 不好的实践
sum = 1+1
sum = 1      +      1

import xxx


# 使用两个空行进行分隔
def add(a, b):
    return a + b


# 使用两个空行进行分隔
class Person:
    # 初始化方法，用于创建对象时设置初始属性
    def __init__(self, name, age):
        self.name = name  # 实例变量
        self.age = age    # 实例变量
    
    # Hello 方法
    def say_hello(self):
        print(f"Hello, my name is {self.name} and I am {self.age} years old.")

# 这两种写法就完全等价
l = [1, 2, 3, 4, 5, 6]
l = [
    1, 2, 3,
    4, 5, 6
]

# 对于字符串而言，以下两种写法完全等价
PI = "3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679821480865132823066470938446095505822317253594081284811174502841027019385211"

PI = "3.1415926535897932384626433832795028841\
971693993751058209749445923078164062862089986\
280348253421170679821480865132823066470938446\
095505822317253594081284811174502841027019385\
211" #换行要顶格

# 这两种写法等价
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = 1
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb = 3
c = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
print(c)

# 需要注意的是，除了首行之外的其余各行都应该在正常的缩进宽度上再加上 4 个空格
c = aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa + \
	bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
print(c)

pri\
nt("Hello, world!")

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa = 1
print(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\
      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa)

\
+-- apple/               // package
|   +-- __init__.py
|   +-- apple1.py        // module
|   `-- apple2.py        // module
|
`-- banana               // package
    +-- __init__.py
    +-- banana1.py       // module
    `-- banana2.py       // module

# Python User\admin\desktop\test_package\__init__.py
# -*- coding: utf-8 -*-
print('Hello,world!')

''' PS C:\Users\admin\desktop> python
>>> import test_package
Hello,world!
>>> import test_package
>>> import test_package
'''

# Good Practice
from math import sqrt
# Bad Practice
import math
from math import *

# Good Practice
# 1. 标准库 imports（按字母顺序）
import os
import sys
from datetime import datetime

# 2. 第三方库 imports（按字母顺序）
import requests
from flask import Flask

# 3. 自定义模块 imports（按字母顺序）
from myproject.models import User
from myproject.utils import helper


# Bad Practice
from myproject.utils import helper
import requests
from datetime import datetime
import os
from flask import Flask
from myproject.models import User
import sys

# Good Practice
# 简洁、直观、高效
print(f"Hello, {name}! You are {age} years old and live in {city}.")
print(f"Next year you'll be {age + 1}.")  # → 31
print(f"{name=}, {age=}")  # → name='Alice', age=30

# Bad Practice
print("Hello, {}! You are {} years old and live in {}.".format(name, age, city))
print("Hello, {name}! You are {age} years old and live in {city}.".format(
    name=name, age=age, city=city
))
next_year = age + 1
print("Next year you'll be {}.".format(next_year))

# 典型使用场景如：状态码
if (status == 1):
    pass

from enum import Enum


class Status(Enum):
    REJECTED = 0     # 被拒绝（替代 BLUE 这种不具语义的名称）
    APPROVED = 1     # 已批准 / 可访问（对应你原来的 Access）
    PENDING = 2      # 待处理

if (status == Status.APPROVED.value):
    pass

# config.ini
[Status]
REJECTED = 0     # 被拒绝（替代 BLUE 这种不具语义的名称）
APPROVED = 1     # 已批准 / 可访问（对应你原来的 Access）
PENDING = 2      # 待处理

# main.py
import configparser


config = configparser.ConfigParser()
config.read('config.ini', encoding='utf-8')
# 示例：获取一个值
approved = config.get('Status', 'APPROVED')
if (status == approved):
    pass

def greet(name: str) -> str:
    return f"Hello, {name}!"

message = greet("Alice")

a, b = 1, 2
# 完全等价于
a = 1
b = 2

a, b = b, a

# 只想循环 5 次，不关心 i 的值
for _ in range(5):
    print("Hello")

# 解包元组，只关心第一个和最后一个
first, _, last = (10, 20, 30)
print(first, last)  # 输出: 10 30

if not a is b  # Bad Practice
if a is not b  # Good Practice

def minus_one(x):
    x -= 1
    return x

# Good Practice
while num:
    num = num if num else minus_one(num)
    print(num)

# Bad Practice
while num is not None:
    num = num if num else minus_one(num)
    print(num)

# Good Practice
if condition1 and condition2 and condition3:
    # 执行操作

# Bad Practice
if condition1:
    if condition2:
        if condition3:
            # 执行操作

# Good Practice
def sum(item):
    head, *tail = items
    return head + sum(tail) if tail else head

# Bad Practice
def sum(item):
    head, *tail = items
    if tail:
        return head + sum(tail)
    else:
        return head

# Good Practice
if isinstance(variable, int):
    pass
# Bad Practice
if type(variable) == int:
    pass

# Good Practice
if x > 0:
    print("Positive")
for i in range(5):
    print(i)
try:
    risky_operation()
except ValueError:
    handle_error()

# Bad Practice
if x > 0: print("Positive")
for i in range(5): print(i)
try: risky_operation() 
except ValueError: handle_error()

# Good Practice
def get_user_age(user_id) -> int:
    if not user_id or user_id not in DATABASE:
        return -1
    return DATABASE[user_id]["age"]  # 总是 int

# Bad Practice
def get_user_age(user_id):
    if not user_id:
        return None          # ← 返回 None
    if user_id == 123:
        return 25            # ← 返回 int
    return "unknown"         # ← 返回 str！

def get_user_age(user_id) -> Optional[int]:
    if not user_id or user_id not in DATABASE:
        return None   # 允许 None，但其他情况一定是 int
    return DATABASE[user_id]["age"]  # 总是 int

def process_data(input_list: list[str]) -> dict[str, int]:
    """接收字符串列表，返回每个字符串及其长度的字典。"""
    output_dict = {}
    for item in input_list:
        output_dict[item] = len(item)
    return output_dict

import pandas as pd

# Good Practice
def modify_database(data):
    # 复制后再修改
    modified_data = data.copy()
    modified_data['age'] = modified_data['age'] + 1
    return modified_data

# Bad Practice
def modify_database(data):
    # 直接修改原始 DataFrame
    data['age'] = data['age'] + 1

# Good Practice
def process_payment(user_id, amount):
    """仅处理支付逻辑"""
    if not is_valid_user(user_id):
        return "Invalid user."
    if not deduct_amount_from_account(user_id, amount):
        return "Insufficient funds."
    if not process_payment_gateway(amount):
        return "Payment processing failed."
    return "Payment successful."

def send_payment_notification(user_id, amount):
    """单独负责发送通知"""
    send_notification(user_id, f"Payment of {amount} processed successfully.")

def make_payment(user_id, amount):
    """主流程：处理支付并通知"""
    result = process_payment(user_id, amount)
    if result == "Payment successful.":
        send_payment_notification(user_id, amount)
    return result

# Bad Practice
def process_payment(user_id, amount):
    """处理用户支付并发送通知"""
    # 步骤1：验证用户
    if not is_valid_user(user_id):
        return "Invalid user."
    # 步骤2：扣款
    if not deduct_amount_from_account(user_id, amount):
        return "Insufficient funds."
    # 步骤3：调用支付网关
    if not process_payment_gateway(amount):
        return "Payment processing failed."
    # 步骤4：发送通知
    send_payment_notification(user_id, amount)
    return "Payment successful."

#  Good Practice
def get_user_email_good(user_data):
    try:
        return user_data["profile"]["email"]
    except KeyError as e:
        # 只捕获我们预期的 KeyError
        missing_key = e.args[0]
        raise ValueError(f"Missing required field: {missing_key}") from e
    except TypeError:
        # 处理 user_data 不是 dict 的情况
        raise TypeError("Expected user_data to be a dictionary") from None

# Bad Practice
def get_user_email_bad(user_data):
    try:
        return user_data["profile"]["email"]
    except:  # 捕获所有异常（包括 KeyboardInterrupt、SystemExit！）
        return None  # 静默返回 None，不记录、不提示

# Good Practice
list_of_jobs = {"Machine learning", "Data Science", "Developer", "CTO", "Writer", "Product Manager"}
found = "CEO" in list_of_jobs
print(found)

# Bad Practice
list_of_jobs = ["Machine learning", "Data Science", "Developer", "CTO", "Writer", "Product Manager"]
found = "CEO" in list_of_jobs
print(found)

# Good Practice
result = [i * 2 for i in range(10)]

# Bad Practice
result = []
for i in range(10):
    result.append(i * 2)

result = [x * y for x in range(10) if x % 2 == 0 for y in range(5) if y > 1 and x + y < 8]

# Good Practice
import functools
from datetime import datetime

def log_calls(func):
    """装饰器：自动记录函数调用信息"""
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        # 统一日志逻辑
        start = datetime.now()
        print(f"[LOG] {start}: Calling {func.__name__} with args={args}, kwargs={kwargs}")
        
        try:
            result = func(*args, **kwargs)
            end = datetime.now()
            print(f"[LOG] {end}: {func.__name__} completed successfully")
            return result
        except Exception as e:
            end = datetime.now()
            print(f"[LOG] {end}: {func.__name__} failed with error: {e}")
            raise
    return wrapper

# 应用装饰器 —— 业务函数干净简洁！
@log_calls
def add_user(name: str, email: str):
    if not name or not email:
        raise ValueError("Name and email required")
    print(f"User {name} added.")

@log_calls
def delete_post(post_id: int):
    if post_id <= 0:
        raise ValueError("Invalid post ID")
    print(f"Post {post_id} deleted.")

# Bad Practice
import time
from datetime import datetime

def add_user(name: str, email: str):
    # 1. 手动写日志（重复代码）
    print(f"[LOG] {datetime.now()}: Calling add_user with args=({name}, {email})")
    
    # 2. 核心业务逻辑（被日志干扰）
    if not name or not email:
        raise ValueError("Name and email required")
    print(f"User {name} added.")
    
    # 3. 又要写返回日志？（更乱）
    print(f"[LOG] {datetime.now()}: add_user completed")

def delete_post(post_id: int):
    # 4. 再次重复日志代码！
    print(f"[LOG] {datetime.now()}: Calling delete_post with args=({post_id})")
    
    if post_id <= 0:
        raise ValueError("Invalid post ID")
    print(f"Post {post_id} deleted.")
    
    print(f"[LOG] {datetime.now()}: delete_post completed")

# Good Practice
with open("myfile.txt", "r") as file:
    'handle the file'
    pass  # 文件会自动关闭

# Bad Practice
file = open("myfile.txt", "r")
'handle the file'
file.close()