用python编写代码，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。

下面是一个简单的好友管理系统的实现示例：

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

class FriendManager:
    def __init__(self):
        self.friends = []
    
    def add_friend(self, friend):
        self.friends.append(friend)
        print(f"{friend.name} has been added to your friend list!")
    
    def remove_friend(self, friend):
        if friend in self.friends:
            self.friends.remove(friend)
            print(f"{friend.name} has been removed from your friend list!")
        else:
            print(f"{friend.name} is not in your friend list!")
    
    def show_friends(self):
        print("Your friend list:")
        for friend in self.friends:
            print(f"Name: {friend.name}, Age: {friend.age}, Gender: {friend.gender}")
    
    def run(self):
        while True:
            print("1. Add a friend")
            print("2. Remove a friend")
            print("3. Show friends")
            print("4. Exit")
            choice = input("Enter your choice (1-4): ")
            
            if choice == "1":
                name = input("Enter name: ")
                age = input("Enter age: ")
                gender = input("Enter gender: ")
                friend = Friend(name, age, gender)
                self.add_friend(friend)
            elif choice == "2":
                name = input("Enter name: ")
                friend = None
                for f in self.friends:
                    if f.name == name:
                        friend = f
                if friend:
                    self.remove_friend(friend)
                else:
                    print(f"{name} is not in your friend list!")
            elif choice == "3":
                self.show_friends()
            elif choice == "4":
                print("Goodbye!")
                break
            else:
                print("Invalid choice, please try again.")

使用示例：

manager = FriendManager()
manager.run()

输出：

1. Add a friend
2. Remove a friend
3. Show friends
4. Exit
Enter your choice (1-4): 1
Enter name: Alice
Enter age: 25
Enter gender: Female
Alice has been added to your friend list!
1. Add a friend
2. Remove a friend
3. Show friends
4. Exit
Enter your choice (1-4): 1
Enter name: Bob
Enter age: 30
Enter gender: Male
Bob has been added to your friend list!
1. Add a friend
2. Remove a friend
3. Show friends
4. Exit
Enter your choice (1-4): 3
Your friend list:
Name: Alice, Age: 25, Gender: Female
Name: Bob, Age: 30, Gender: Male
1. Add a friend
2. Remove a friend
3. Show friends
4. Exit
Enter your choice (1-4): 2
Enter name: Alice
Alice has been removed from your friend list!
1. Add a friend
2. Remove a friend
3. Show friends
4. Exit
Enter your choice (1-4): 3
Your friend list:
Name: Bob, Age: 30, Gender: Male
1. Add a friend
2. Remove a friend
3. Show friends
4. Exit
Enter your choice (1-4): 4
Goodbye!