justdoit0823/oneof_type_in_protocol_buffers.md

Last active April 6, 2018 14:45

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How oneof type works in protocol buffers.

Raw

If you have a message with many fields and where at most one field will be set at the same time, you can enforce this behavior and save memory by using the oneof feature.

Oneof fields are like regular fields except all the fields in a oneof share memory, and at most one field can be set at the same time. Setting any member of the oneof automatically clears all the other members. You can check which value in a oneof is set (if any) using a special case() or WhichOneof() method, depending on your chosen language.

This type may have no any fields, and can't have exact one field.