Python else分支运行时触发UnboundLocalError报错排查

报错和缩进、全局变量作用域无关，是两处代码逻辑错误导致：

1. 所有*_key_flag匹配标志位没有提前初始化，只有当日志某一行命中对应key时，变量才会被赋值。如果某个key在整个日志文件里完全没出现，对应的flag变量从未被创建，循环结束后做全量flag判断时，就会触发UnboundLocalError: local variable 'xxx' referenced before assignment错误。
2. 逐行匹配的逻辑写反：当前代码每遍历一行，只要该行不包含目标key就往错误列表追加报错，会导致即使key在其他行已经命中，只要某一行不匹配就重复写入错误信息，最终错误列表会充斥大量无效重复内容，完全不符合“仅记录缺失key”的预期。

• 进入日志遍历逻辑前，先把所有*_key_flag初始化为0（代表未匹配状态），同时清空全局错误列表，避免上次函数调用的残留信息干扰本次结果
• 遍历日志行时仅做匹配操作：命中对应key就把相关flag置为1，不在逐行循环内做错误信息追加
• 整个日志文件遍历完成后，再统一检查所有flag的状态，对值为0（未匹配）的key，追加对应的错误信息到列表
• 最终判断所有flag是否均为1，是则返回True并打印校验通过提示，否则返回False并打印缺失key的错误列表

import datetime
import os.path
import logging

recipe_name = 'Sanity_CS.py'
NR_log = 'NR_' + str(datetime.datetime.now()).split()[0] + '.log'
lst = []


def pre_conditions():
    # 清空历史错误记录
    lst.clear()
    # 提前初始化所有匹配标志位为未匹配状态
    name_key_flag = 0
    app_key_flag = 0
    api_key_flag = 0
    lot_key_flag = 0
    recipe_key_flag = 0
    wafer_key_flag = 0
    recipe_pause_key_flag = 0
    program_key_flag = 0
    recipe_creation_key_flag = 0

    # 定义待匹配key
    name_key = recipe_name
    app_key = 'Application was powered-up successfully, mode is: Review'
    api_key = 'API recipe was chosen'
    lot_key = 'Lot was created successfully'
    recipe_key = 'Recipe execution started'
    wafer_key = 'The Wafer was loaded successfully'
    recipe_pause_key = 'Recipe run is paused'
    program_key = 'Moving to Program mode'
    recipe_creation_key = 'Recipe was saved successfully under the name: sanity_2022-06-22_Ver_5.1'

    with open(NR_log, 'r') as logfile:
        for line in logfile:
            # 逐行匹配，命中则更新对应标志位
            if name_key in line:
                name_key_flag = 1
            if app_key in line:
                app_key_flag = 1
            if api_key in line:
                api_key_flag = 1
            if lot_key in line:
                lot_key_flag = 1
            if recipe_key in line:
                recipe_key_flag = 1
            if wafer_key in line:
                wafer_key_flag = 1
            if recipe_pause_key in line:
                recipe_pause_key_flag = 1
            if program_key in line:
                program_key_flag = 1
            if recipe_creation_key in line:
                recipe_creation_key_flag = 1

    # 遍历完所有日志后，统一收集未匹配项的错误信息
    if name_key_flag != 1:
        lst.append('\nError: Script was not successfully executed \n')
    if app_key_flag != 1:
        lst.append('\nError: Application was failed to power up.\n')
    if api_key_flag != 1:
        lst.append("\nError: Recipe type [API] was not successfully chosen\n")
    if lot_key_flag != 1:
        lst.append("\nError: A lot was not successfully created.\n")
    if recipe_key_flag != 1:
        lst.append("\nError: A timeout, recipe was not executed\n")
    if wafer_key_flag != 1:
        lst.append("\nError: The wafer was not loaded.\n")
    if recipe_pause_key_flag != 1:
        lst.append("\nError: The recipe was not paused.\n")
    if program_key_flag != 1:
        lst.append("\nError: The script was not switch to program key.\n")
    if recipe_creation_key_flag != 1:
        lst.append("\nError: The recipe was not saved.\n")

    # 最终校验结果判断
    all_match = all([
        name_key_flag == 1,
        app_key_flag == 1,
        api_key_flag == 1,
        lot_key_flag == 1,
        recipe_key_flag == 1,
        wafer_key_flag == 1,
        recipe_pause_key_flag == 1,
        program_key_flag == 1,
        recipe_creation_key_flag == 1
    ])
    if all_match:
        print("Pre conditions are OK.")
        return True, lst
    else:
        print("Missing keys found:", lst)
        return False, lst

内容的提问来源于stack exchange，提问作者I'm not a robot