Python while循环无法识别变量状态变更的问题排查

开发用户名输入校验逻辑时，预期实现效果：当用户输入的名称包含数字、特殊符号等非普通字母内容时，程序提示用户重新输入。
实际运行异常：while循环始终无法识别校验状态变量的变更，无论输入什么内容都会持续执行循环逻辑，初步推测问题与def定义的函数内部修改变量的作用域机制有关。
原始实现代码如下：

from cgi import test
from re import T
import time
import math

big_nono_numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9,]
big_nonosymbols = ["!", "@", "#", "$", "%", "^", "&", "*", "(", ")", "-", "", "=", "+", ":", ";", "{", "}", "[", "]", "'", ">", "<", "/", "?"]
yesyesyesses = ['yes', 'y', 'ye', 'ys', 'k', 'ok', 'sure', 'alright', 'okay']
nononoes = ['no', 'n', 'nah', 'na', 'never', 'i dont', 'not really', 'im good',]
v1 = False
v2 = False
v3 = True

def space():
    print('')
    
def validate1():
    if i2.find('`') >=0:
        v2 = False
    elif i2.find('~') >=0:
        v2 = False
    elif i2.find('!') >=0:
        v2 = False
    elif i2.find('@') >=0:
        v2 = False
    elif i2.find('#') >=0:
        v2 = False
    elif i2.find('$') >=0:
        v2 = False
    elif i2.find('%') >=0:
        v2 = False
    elif i2.find('^') >=0:
        v2 = False
    elif i2.find('&') >=0:
        v2 = False
    elif i2.find('*') >=0:
        v2 = False
    elif i2.find('(') >=0:
        v2 = False
    elif i2.find(')') >=0:
        v2 = False
    elif i2.find('-') >=0:
        v2 = False
    elif i2.find('=') >=0:
        v2 = False
    elif i2.find('_') >=0:
        v2 = False
    elif i2.find('+') >=0:
        v2 = False
    elif i2.find('[') >=0:
        v2 = False
    elif i2.find('{') >=0:
        v2 = False
    elif i2.find(']') >=0:
        v2 = False
    elif i2.find('}') >=0:
        v2 = False
    elif i2.find('|') >=0:
        v2 = False
    elif i2.find(';') >=0:
        v2 = False
    elif i2.find(':') >=0:
        v2 = False
    elif i2.find("'") >=0:
        v2 = False
    elif i2.find('"') >=0:
        v2 = False
    elif i2.find(',') >=0:
        v2 = False
    elif i2.find('<') >=0:
        v2 = False
    elif i2.find('.') >=0:
        v2 = False
    elif i2.find('>') >=0:
        v2 = False
    elif i2.find('/') >=0:
        v2 = False
    elif i2.find('?') >=0:
        v2 = False
    elif i2.find('0') >=0: 
        v2 = False
    elif i2.find('1') >=0:
        v2 = False
    elif i2.find('2') >=0:
        v2 = False
    elif i2.find('3') >=0:
        v2 = False
    elif i2.find('4') >=0:
        v2 = False
    elif i2.find('5') >=0:
        v2 = False
    elif i2.find('6') >=0:
        v2 = False
    elif i2.find('7') >=0:
        v2 = False
    elif i2.find('8') >=0:
        v2 = False
    elif i2.find('9') >=0:
        v2 = False
    else:
        v2 = True
    print(v2)
    
def test():
    print(1)
    
chatbot_run = True


space
print('Welcome to Astronaugt-for-hire!')
time.sleep(1)
i1 = input('Do you want to hire an astronaught? ')
if i1 in yesyesyesses:
    v1 = True
    space
    time.sleep(3)   
    print("That's Great! First you will have to create an account.")
elif i1 in nononoes:
    v1 = True
    time.sleep(2)
    print('WELL TOO BAD! YOU ARE ANYWAY. Time to make an account.')
while v1 == False:
    i1 = input('Could you say that again? ')
    if i1 in yesyesyesses:
        v1 = True
        time.sleep(3)
        print("That's Great! First you will have to create an account.")
    elif i1 in nononoes:
        v1 = True
        time.sleep(1)
        print('WELL TOO BAD! YOU ARE ANYWAY. Time to make an account.')

time.sleep(1)
print('Lets start.')

time.sleep(1.5)
i2 = input('Step 1. What is your name? ')
validate1()
test()

while v2 == False:
    i2 = input('please try again')
    validate1()

• 核心原因是Python变量作用域规则：在validate1()函数内部给v2赋值时，Python默认将v2识别为函数内的局部变量，不会修改全局作用域下初始值为False的v2。外层while循环判断的始终是全局的v2，自然会无限执行。
• 附带代码问题：
  • 所有调用space的位置都没加括号，仅写函数名不会执行打印空行的逻辑，只是引用了函数对象。
  • validate1直接读取全局变量i2，函数和外层逻辑耦合度极高，不利于维护。
  • 逐字符调用find判断非法字符的写法冗余度极高，几十行判断完全可以用内置字符串方法简化。

快速修复（仅解决当前作用域问题） #

在validate1函数开头添加global v2声明，明确告诉Python函数内操作的v2是全局变量，同时把所有space调用改为space()补全括号。

def validate1():
    global v2 # 新增全局变量声明
    # 原有判断逻辑不变

规范修复（推荐，彻底规避全局变量问题） #

废弃全局变量传值的写法，让校验函数接收待校验字符串作为入参，直接返回布尔类型的校验结果，同时用字符串内置方法简化校验逻辑：

def space():
    print('')

def validate1(input_str):
    # 只要输入包含任意非字母字符，就返回校验不通过
    for char in input_str:
        if not char.isalpha():
            return False
    return True

对应调整主逻辑里的调用方式，直接用函数返回值做循环判断，不需要额外维护全局状态变量：

space()
print('Welcome to Astronaugt-for-hire!')
time.sleep(1)
i1 = input('Do you want to hire an astronaught? ')
v1 = False
if i1 in yesyesyesses:
    v1 = True
    space()
    time.sleep(3)   
    print("That's Great! First you will have to create an account.")
elif i1 in nononoes:
    v1 = True
    time.sleep(2)
    print('WELL TOO BAD! YOU ARE ANYWAY. Time to make an account.')
while v1 == False:
    i1 = input('Could you say that again? ')
    if i1 in yesyesyesses:
        v1 = True
        time.sleep(3)
        print("That's Great! First you will have to create an account.")
    elif i1 in nononoes:
        v1 = True
        time.sleep(1)
        print('WELL TOO BAD! YOU ARE ANYWAY. Time to make an account.')

time.sleep(1)
print('Lets start.')

time.sleep(1.5)
i2 = input('Step 1. What is your name? ')
while not validate1(i2):
    i2 = input('输入包含数字或特殊符号，请重新输入：')

内容的提问来源于stack exchange，提问作者MISTERME