枚举，类，命名空间和长名称

Question

From what I understand, enums that relates to a class should be declared inside the class, like this:

namespace Sensors {
class MySensor {
 public:
     enum class SensorStatus {
         kSensorActive,
         kSensorInactive
     }
     SensorStatus GetCurrentStatus(void);
};
}

The problem I'm having with this, is that it leads to the following code in another part of the program.

 Sensors::MySensor::SensorStatus current_status = mySensor.GetStatus();
 switch (current_status):
     case Sensors::MySensor::SensorStatus::kSensorActive:  // 47 characters!
          printf("Sensor is active.");
          break;
     case Sensors::MySensor::SensorStatus::kSensorInactive:  // 49 characters!
          printf("Sensor is inactive.");
          break;

I appreciate that its very clear what kSensorActive and kSensorInactive refers to, no ambiguity there. But if you try to follow a style guide that specifies 80 characters, we end up with a lot of line breaks, which reduces clarity, IMHO. One example of a long line comes if we have a function that takes two different enumerators; MyFunction(NamespaceA::MyFirstClass::MyFirstEnum::AnEnumerator, NamespaceB::MySecondClass::MySecondEnum::ADifferentEnumerator) - a whopping 127 characters.

Is it common with these long names or am I missing something?

Answer 1

To reduce the length without reducing the overall scope clarity you have at least 2 options:

1. Alias types ie. using Status = Sensors::MySensor::SensorStatus;
2. A typedef ie. typedef Sensors::MySensor::SensorStatus Status2;

Use these inside the scope of this function so it is local and the ambiguous name doesnt spread throughout the code. Here is a live example.

Answer 2

First, you repeat stuff:

The name kSensorActive doesn't have to say Sensor if you already specified that it's a SensorStatus in the name. Or you could remove Sensor from SensorStatus if it's inside MySensor . Maybe both.

The idea behind wrapping things inside classes and namespaces is that you CAN use the same name over and over again, for something that is "the same sort of thing", rather than having completely unique names throughout.

You can also, locally, change the names with using , something like this

using Status = Sensors::MySensor::SensorStatus;

and then us Status::kSensorActive where you previously used the long thing.