Python调用多返回值函数报too many values to unpack(expected 2)错误排查

错误根因 #

该报错由Python的语句换行规则导致：Python默认以换行作为单个语句的结束标志，你的代码中两处多行元组的写法不符合语法要求，导致执行逻辑和预期不符：

1. 赋值接收端逻辑错误：16个接收变量拆分为5行书写，既没有用圆括号包裹所有变量，也没有在每行末尾添加续行符\。Python会将前4行识别为无赋值动作的独立元组表达式（直接丢弃执行结果），仅将最后一行的2个变量作为赋值接收端，因此报错提示预期仅2个值。
2. 函数返回端逻辑错误：return后的16个返回值同样拆分为多行书写，未添加括号或续行符。Python仅会将return所在第一行的4个值作为函数返回结果，后续行的内容会被识别为函数外的独立代码，不会被返回。

修复方案 #

推荐将所有多行元组用圆括号包裹，Python会自动识别括号内的换行为续行，无需添加额外符号：

1. 调用侧赋值代码修改 #

(
    self.action_heatCoefficientSpaceHeating, self.action_heatCoefficientDHW, self.action_chargingPowerEV, self.state_temperatureBufferStorage,
    self.state_usableVolumeDHWTank, self.state_SOCOfTheEV, self.help_countNumberOfStartHeatPump_HeatingBufferStorage_Indiviual, self.help_countNumberOfStartHeatPump_HeatingDHW_Indiviual,
    self.help_countNumberOfStartHeatPump_Heating_Combined , self.helpCounterNumberOfRunningSlots_SpaceHeating , self.helpCounterNumberOfRunningSlots_DHW ,
    self.helpCounterNumberOfRunningSlots_Combined , self.helpCounterNumberOfStandBySlots_SpaceHeating , self.helpCounterNumberOfStandBySlots_DHW ,
    self.helpCounterNumberOfStandBySlots_Combined, self.helpCurrentPeakLoad
) = ICSimulation.simulateTimeSlot_WithAddtionalControler_BT1(
    self.action_heatCoefficientSpaceHeating, self.action_heatCoefficientDHW, self.action_chargingPowerEV, self.help_statePreviousTimeSlot_temperatureBufferStorage,
    self.help_statePreviousTimeSlot_usableVolumeDHWTank, self.help_statePreviousTimeSlot_SOCOfTheEV, self.help_countNumberOfStartHeatPump_HeatingBufferStorage_Indiviual,
    self.help_countNumberOfStartHeatPump_HeatingDHW_Indiviual, self.help_countNumberOfStartHeatPump_Heating_Combined , self.helpCounterNumberOfRunningSlots_SpaceHeating , self.helpCounterNumberOfRunningSlots_DHW ,
    self.helpCounterNumberOfRunningSlots_Combined , self.helpCounterNumberOfStandBySlots_SpaceHeating , self.helpCounterNumberOfStandBySlots_DHW , self.helpCounterNumberOfStandBySlots_Combined, self.helpCurrentPeakLoad
)

2. 函数返回代码修改 #

def simulateTimeSlot_WithAddtionalControler_BT1 (action_SpaceHeating, action_DHWHeating, action_EVCharging, state_BufferStorageTemperatureLastTimeSlot,
                                                 state_usableVolumeDHWLastTimeSlot, state_SOCofEVLastTimeSlot, helpCountNumberOfStartsIndividual_SpaceHeating, 
                                                 helpCountNumberOfStartsIndividual_DHW, helpCountNumberOfStarts_Combined , helpCounterNumberOfRunningSlots_SpaceHeating , helpCounterNumberOfRunningSlots_DHW ,
                                                 helpCounterNumberOfRunningSlots_Combined , helpCounterNumberOfStandBySlots_SpaceHeating , helpCounterNumberOfStandBySlots_DHW ,
                                                 helpCounterNumberOfStandBySlots_Combined, helpCurrentPeakLoad ):

    
    state_BufferStorageTemperatureCurrent =-1
    state_usableVolumeDHWCurrent = -1
    state_SOCofEVCurrent = -1
    action_SpaceHeating_corrected = -1
    action_DHWHeating_corrected = -1
    action_EVCharging_corrected = -1
    
    # 用括号包裹所有返回值
    return (
        action_SpaceHeating_corrected, action_DHWHeating_corrected, action_EVCharging_corrected, state_BufferStorageTemperatureCurrent,
        state_usableVolumeDHWCurrent, state_SOCofEVCurrent, helpCountNumberOfStartsIndividual_SpaceHeating, helpCountNumberOfStartsIndividual_DHW,
        helpCountNumberOfStarts_Combined , helpCounterNumberOfRunningSlots_SpaceHeating , helpCounterNumberOfRunningSlots_DHW ,
        helpCounterNumberOfRunningSlots_Combined , helpCounterNumberOfStandBySlots_SpaceHeating , helpCounterNumberOfStandBySlots_DHW ,
        helpCounterNumberOfStandBySlots_Combined, helpCurrentPeakLoad
    )

内容的提问来源于stack exchange，提问作者PeterBe