浅拷贝与深拷贝区别之技术方案及应用实例解析

// JavaScript
const defaults = {theme: 'light', fontSize: 16};
const userSettings = {fontSize: 18, showSidebar: true};
const mergedSettings = Object.assign({}, defaults, userSettings);

# Python
original = [1, [2, 3], 4]
copied = list(original)  # 等价于 original[:]
copied[1][0] = 99  # 修改嵌套列表中的元素，会影响原始数组

// JavaScript
const original = {
  config: {apiKey: 'secret', timeout: 3000},
  data: [1, {value: 100}]
};
const clone = JSON.parse(JSON.stringify(original));
clone.config.apiKey = 'newKey';  // 不会影响原始对象

# Python
import copy
class GameState:
    def __init__(self, score, inventory):
        self.score = score
        self.inventory = inventory

original = GameState(100, ['sword', 'shield'])
backup = copy.deepcopy(original)

function shallowCopy(source) {
  if (typeof source !== 'object' || source === null) {
    return source;  // 非对象类型直接返回
  }
  
  if (Array.isArray(source)) {
    return [...source];  // 数组使用扩展运算符
  }
  
  return {...source};  // 对象使用扩展运算符
}

// 使用示例
const original = {a: 1, b: [2, 3]};
const copy = shallowCopy(original);

import copy

class DeepCopyUtil:
    @staticmethod
    def copy(obj, exclude_fields=None):
        """
        深拷贝对象，可排除特定字段
        :param obj: 待拷贝的对象
        :param exclude_fields: 要排除的字段列表
        :return: 深拷贝后的对象
        """
        if exclude_fields is None:
            exclude_fields = []
        
        # 如果是字典类型，处理排除字段
        if isinstance(obj, dict):
            return {
                k: DeepCopyUtil.copy(v, exclude_fields)
                for k, v in obj.items()
                if k not in exclude_fields
            }
        
        # 如果是列表类型，递归处理每个元素
        if isinstance(obj, list):
            return [DeepCopyUtil.copy(item, exclude_fields) for item in obj]
        
        # 处理自定义对象
        if hasattr(obj, '__dict__'):
            clone = obj.__class__()
            for attr, value in obj.__dict__.items():
                if attr not in exclude_fields:
                    setattr(clone, attr, DeepCopyUtil.copy(value, exclude_fields))
            return clone
        
        # 基本类型直接返回
        return copy.copy(obj)

# 使用示例
class User:
    def __init__(self, name, config):
        self.name = name
        self.config = config

user = User("Alice", {"theme": "dark"})
cloned = DeepCopyUtil.copy(user, exclude_fields=['config'])

import React, {useState} from 'react';

function DataEditor({initialData}) {
  // 使用深拷贝初始化状态，避免直接修改原始数据
  const [data, setData] = useState(() => {
    return JSON.parse(JSON.stringify(initialData));
  });

  const handleChange = (e) => {
    // 创建数据副本进行修改
    const newData = JSON.parse(JSON.stringify(data));
    newData[e.target.name] = e.target.value;
    setData(newData);
  };

  return (
    <div>
      <input 
        type="text" 
        name="username" 
        value={data.username} 
        onChange={handleChange} 
      />
      {/* 其他表单字段 */}
    </div>
  );
}