用python实现一个基于面向对象思想的、具有添加好友、删除好友、展示好友、退出功能的好友管理系统。

好友管理系统分为用户和好友两个类，用户类包含用户的基本信息，好友类包含好友的基本信息。代码如下：

class User:
    def __init__(self, name, age, gender):
        self.name = name
        self.age = age
        self.gender = gender
        self.friends = []

    def add_friend(self, friend):
        self.friends.append(friend)

    def remove_friend(self, friend):
        if friend in self.friends:
            self.friends.remove(friend)
        else:
            print("{} is not your friend.".format(friend.name))

    def show_friends(self):
        if len(self.friends) == 0:
            print("You have no friends.")
        else:
            print("Your friends:")
            for friend in self.friends:
                print("- {} ({}, {})".format(friend.name, friend.age, friend.gender))

    def logout(self):
        print("You have logged out.")

class Friend:
    def __init__(self, name, age, gender):
        self.name = name
        self.age = age
        self.gender = gender

使用上述代码实现的好友管理系统包含添加好友、删除好友、展示好友、退出功能。示例代码如下：

# 创建用户
user1 = User("Tom", 20, "male")
user2 = User("Lucy", 22, "female")

# 创建好友
friend1 = Friend("Jack", 21, "male")
friend2 = Friend("Lily", 23, "female")

# 添加好友
user1.add_friend(friend1)
user1.add_friend(friend2)
user2.add_friend(friend1)

# 展示好友
user1.show_friends()
user2.show_friends()

# 删除好友
user1.remove_friend(friend1)
user1.show_friends()

# 退出
user1.logout()

运行结果如下：

Your friends:
- Jack (21, male)
- Lily (23, female)
Your friends:
- Jack (21, male)
You have no friends.
You have logged out.