Assign RepeatedPtrField to repeated field in a protobuf message

Question

I have a RepeatedPtrField<M::Table> and a protobuf message M as:

message M {
  message Table {
    optional string guid = 1;
    optional int64 schema_version = 2;
    optional int64 data_version = 3;
    repeated Column column = 4;
  }
  repeated Table table = 1;
}

How to I create a instance of M having the contents of RepeatedPtrField. I can write a for loop to copy data explicitly, but I am currently looking for something more concise, preferably using std::move() like optimization.

I did `state.mutable_table()->Swap(&table);`, where table was the RepeatedPtrField, and it worked — v78, Dec 30 '19 at 08:17

score 1 · Accepted Answer · answered Dec 31 '19 at 02:33

If you're using a new version of Protobuf, like Protobuf 3.6.0, RepeatedPtrField defines move constructor, and you can call std::move to achieve your goal.

If you're using an old version, you have to call Swap to do the work, as you mentioned in the comment.

Assign RepeatedPtrField to repeated field in a protobuf message

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