python - python 通过两个函数维护列表

Question

我正在尝试使用 python 创建一个字符选择 CLI。

我想显示用户当前选择的角色队伍，以便他们可以看到他们已经选择了谁。用户不能两次选择相同的字符。用户必须有 4 个字符才能继续

我创建了以下代码(我确实正确调用了它，不用担心!):

def ChooseCharacters():
    CharList=[]
    CurrentParty=[]
    print("Select up to 4 explorers!")
    while len(CharList)!=4:
        if len(CharList)!=4:
            if len(CharList)==0:
                pass
            else:
                for CharID in list(set(CharList)):
                    print(CharList)
                    SQL=("SELECT firstname,secondname FROM characters WHERE CharID=%s")
                    mycursor.execute(SQL,(CharID,))
                    myresult=mycursor.fetchone()
                    Name=(myresult[0]+" "+myresult[1])
                    CurrentParty= list(set(CurrentParty))
                    CurrentParty.append(Name)
                print("Current Party: ",CurrentParty)
        PrintChoice(CharList)
def PrintChoice(CharList):
    mycursor.execute("SELECT * FROM characters")
    myresults=mycursor.fetchall()
    Num=0
    for char in myresults:
        Num = Num + 1
        print(str(Num)+("."),char[1],char[2])
    Choice=input("Select Character: ")
    if Choice in CharList:
        print("Character already selected!")
        return
    CharList.append(Choice)
    print(CharList)

看起来所选的第一个字符在列表中重复，其余代码工作正常。

预期结果

Current Party:  ['Sam Jordan']

Current Party:  ['Sam Jordan','Olivia Cope']

Current Party:  ['Sam Jordan','Olivia Cope','Dylan Nesbitt']

实际结果

Current Party:  ['Sam Jordan']

Current Party:  ['Olive Cope', 'Sam Jordan', 'Sam Jordan']

Current Party:  ['Sam Jordan', 'Olive Cope', 'Dylan Nesbitt', 'Sam Jordan']

我无法确定第一个输入的第二次复制发生在哪里，因为第一个输入输出正确。

如果您需要查看数据库表，请询问。

Answer 1

您当前的代码有点难以理解，因为它混合了非常不同类型的事件:从数据库读取、让用户交互式地做出选择以及常规算法逻辑。此外，代码依赖于一种通常最好尽可能避免的模式——即将数据结构传递给其他函数，以便其他函数可以修改它们。编写获取数据并返回新数据的函数通常更简单，也是明智的做法。

我建议您重构它以进行一些更清晰的分离，而不是困惑如何修复当前的代码。这是一个快速说明:

import string

# A top-level function to orchestrate things.
def choose_characters():
    chars = get_characters_from_db(12)  # Read 12 from DB.
    selected = select_items(chars, 4)   # Select 4 of them.
    print(selected)

# One or more functions to interact with the database.
# In this example we just return some mock data.
def get_characters_from_db(n):
    return string.ascii_uppercase[0:n]

# A general function to have a user select N items.
def select_items(xs, n):
    selected = []
    print('Choices:')
    for i, x in enumerate(xs):
        print(i + 1, x)
    print()
    while len(selected) < n:
        s = input('=> ')
        try:
            i = int(s) - 1
            x = xs[i]
        except Exception:
            print('Invalid entry')
            continue
        if x in selected:
            print('Already selected')
        else:
            selected.append(x)
    print()
    return selected

choose_characters()