public string Undo()
{
switch (_prevSpeed)
{
case Fan.High:
return(_fan.SetHigh());
case Fan.Medium:
return(_fan.SetMedium());
case Fan.Low:
return(_fan.SetLow());
case Fan.Off:
return(_fan.SetOff());
default:
return("fan set speed error");
}
}
public string Undo()
{
if (_prevSpeed.Equals(Fan.High))
{
_fan.SetHigh();
}
if (_prevSpeed.Equals(Fan.Medium))
{
_fan.SetMedium();
}
if (_prevSpeed.Equals(Fan.Low))
{
_fan.SetLow();
}
if (_prevSpeed.Equals(Fan.Off))
{
_fan.SetOff();
}
return("fan set speed error");
}
