Hands-On RESTful Web Services with Go - Second Edition

Enumerations and repeated fields

Enumerations (enum) provide the ordering of numbers for a given set of elements. The default order of values is from 0 to n. So, in a protocol buffer message, we can have an enumeration type. Let's look at an example of the enum:

syntax 'proto3'; message Schedule{  enum Days{     SUNDAY = 0;     MONDAY = 1;     TUESDAY = 2;     WEDNESDAY = 3;     THURSDAY = 4;     FRIDAY = 5;     SATURDAY = 6;  }}

What if we have to assign the same values for the multiple enumeration members?

Protobuf3 has an option called allow_alias that we can use to assign two different members the same value, like so:

enum EnumAllowingAlias {
  option allow_alias = true;
  UNKNOWN = 0;
  STARTED = 1;
  RUNNING = 1;
}

Here, STARTED and RUNNING both have a 1 tag. This means ...