Add Day_3: 函数与异常(日志/参数校验)

Day_3/参考解答.py

@@ -0,0 +1,112 @@
+# -*- coding: utf-8 -*-
+"""
+Day_3 参考解答
+=============
+主题：函数与异常。
+建议：先自己写，写不出来再看；看完后关掉文件自己默写一遍。
+"""
+
+import time
+
+# ============================================================
+# 题目一：万能日志记录器
+# ============================================================
+
+def log_call(func, label=""):
+    """给函数包一层日志。func 被调用时打印参数和耗时。"""
+    def wrapper(*args, **kwargs):
+        tag = f"[{label}] " if label else ""
+        print(f"{tag}[LOG] 调用函数 {func.__name__}，参数为 args={args}, kwargs={kwargs}")
+        start = time.time()
+        result = func(*args, **kwargs)      # 原样透传参数
+        elapsed = time.time() - start
+        print(f"{tag}[LOG] {func.__name__} 执行完成，耗时 {elapsed:.4f} 秒")
+        return result                       # 原样返回结果
+    return wrapper
+
+
+@log_call                        # 等价于 add = log_call(add)
+def add(a, b):
+    return a + b
+
+
+def multiply(a, b):
+    return a * b
+
+multiply = log_call(multiply, label="核心计算")   # 进阶：带标签
+
+
+if __name__ == '__main__':
+    print(add(1, 2))
+    print(multiply(3, 4))
+    # 输出示例：
+    # [LOG] 调用函数 add，参数为 args=(1, 2), kwargs={}
+    # [LOG] add 执行完成，耗时 0.0000 秒
+    # 3
+    # [核心计算][LOG] 调用函数 multiply，参数为 args=(3, 4), kwargs={}
+    # [核心计算][LOG] multiply 执行完成，耗时 0.0000 秒
+    # 12
+
+
+# ============================================================
+# 题目二：模拟注册接口的参数校验
+# ============================================================
+
+class ValidationError(Exception):
+    """自定义校验异常：参数不合法时抛出"""
+    pass
+
+
+def validate_registration(data):
+    username = data.get("username")
+    email = data.get("email")
+    age = data.get("age")
+
+    if not username or len(username) < 3:
+        raise ValidationError("用户名必须存在且长度不少于 3")
+    if not email or "@" not in email or "." not in email:
+        raise ValidationError("邮箱必须包含 @ 和 .")
+    if age is None:
+        raise ValidationError("年龄必须存在")
+    try:
+        age_int = int(age)                  # 字符串 "20" 也能转
+    except (TypeError, ValueError):
+        raise ValidationError("年龄必须是整数")
+    if not (1 <= age_int <= 120):
+        raise ValidationError("年龄必须在 1~120 之间")
+
+
+def register():
+    data = {"username": "zhangsan", "email": "zs@163.com", "age": "20"}
+    try:
+        validate_registration(data)
+        print(f"注册成功，欢迎 {data['username']}！")
+    except ValidationError as e:
+        print(f"校验失败: {e}")
+
+
+# ---- 进阶：把规则做成数据 ----
+def is_valid_email(email):
+    return isinstance(email, str) and "@" in email and "." in email
+
+
+def validate(data, rules):
+    """rules: {字段名: (校验函数, 错误信息)}，返回所有错误列表"""
+    errors = []
+    for field, (check, message) in rules.items():
+        if not check(data.get(field)):
+            errors.append(f"{field}: {message}")
+    return errors
+
+
+RULES = {
+    "username": (lambda v: isinstance(v, str) and len(v) >= 3, "用户名长度不足 3"),
+    "email": (is_valid_email, "邮箱格式不正确"),
+    "age": (lambda v: isinstance(v, int) and 1 <= v <= 120, "年龄非法"),
+}
+
+
+if __name__ == '__main__':
+    register()                                   # 注册成功，欢迎 zhangsan！
+    print(validate({"username": "zs", "email": "bad", "age": 200}, RULES))
+    # ['username: 用户名长度不足 3', 'email: 邮箱格式不正确', 'age: 年龄非法']