我正在阅读EssentialC#3.0一书，想知道这是否是检查委托(delegate)是否为null的好方法？:classThermostat{publicdelegatevoidTemperatureChangeHandler(floatnewTemperature);publicTemperatureChangeHandlerOnTemperatureChange{get;set;}floatcurrentTemperature;publicfloatCurrentTemperature{get{returnthis.currentTemperature;}set{if(curre