Reserved keyword usage in protobuf 2.5.0

[Marcos Juarez]

I ran into a situation today in which I needed to use the "reserved" keyword in a protobuf definition, so that in the future, nobody would use those fields.  I've attached a screenshot of what the docs say, from https://developers.google.com/protocol-buffers/docs/proto#reserved 

However, when I try to use that keyword in an actual message with field definitions, protoc always complains with the following error:

Expected "required", "optional", or "repeated".

My protobuf definition looks like this:

message MyMessage {

      // Some comments

      reserved, 4, 108, 109;

      

      // Some more comments

      required string event_uuid            = 1     ;

      required string date                  = 2     ;

      required string timezone              = 3     ;

      optional string field1                = 101   ;

      optional string field2                = 110   ;

}

     

Am I reading that spec wrong, or is the reserved keyword broken?

Marcos

[Ilia Mirkin]

On Wed, May 25, 2016 at 5:44 PM, Marcos Juarez <mju...@gmail.com> wrote:

I ran into a situation today in which I needed to use the "reserved" keyword in a protobuf definition, so that in the future, nobody would use those fields.  I've attached a screenshot of what the docs say, from https://developers.google.com/protocol-buffers/docs/proto#reserved 

However, when I try to use that keyword in an actual message with field definitions, protoc always complains with the following error:

Expected "required", "optional", or "repeated".

My protobuf definition looks like this:

message MyMessage {

      // Some comments

      reserved, 4, 108, 109;

Did you mean "reserved 4, 108, 109;"?

  -ilia

[Marcos Juarez]

I just realized, there's a typo in my example.  It should say:  

   reserved 4, 108, 109;

Note there's no comma after the reserved keyword.  

Also, I checked, and the protoc compiler I'm using reports itself as:  libprotoc 2.5.0

[Feng Xiao]

On Wed, May 25, 2016 at 5:49 PM, Marcos Juarez <mju...@gmail.com> wrote:

I just realized, there's a typo in my example.  It should say:  

   reserved 4, 108, 109;

Note there's no comma after the reserved keyword.  

Also, I checked, and the protoc compiler I'm using reports itself as:  libprotoc 2.5.0

The reserved keyword was added in v3.0.0-alpha-3:

https://github.com/google/protobuf/releases/tag/v3.0.0-alpha-3

You have to upgrade your protobuf version to use it.

 

On Wed, May 25, 2016 at 3:44 PM, Marcos Juarez <mju...@gmail.com> wrote:

I ran into a situation today in which I needed to use the "reserved" keyword in a protobuf definition, so that in the future, nobody would use those fields.  I've attached a screenshot of what the docs say, from https://developers.google.com/protocol-buffers/docs/proto#reserved 

However, when I try to use that keyword in an actual message with field definitions, protoc always complains with the following error:

Expected "required", "optional", or "repeated".

My protobuf definition looks like this:

message MyMessage {

      // Some comments

      reserved, 4, 108, 109;

      

      // Some more comments

      required string event_uuid            = 1     ;

      required string date                  = 2     ;

      required string timezone              = 3     ;

      optional string field1                = 101   ;

      optional string field2                = 110   ;

}

     

Am I reading that spec wrong, or is the reserved keyword broken?

Marcos

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[Marcos Juarez]

Thanks Feng.  

It does look like the documentation is wrong then.  I checked, and the "Reserved" section shows up when looking at the Language Guide for both proto2 and proto3.

[Feng Xiao]

On Thu, May 26, 2016 at 12:25 PM, Marcos Juarez <mju...@gmail.com> wrote:

Thanks Feng.  

It does look like the documentation is wrong then.  I checked, and the "Reserved" section shows up when looking at the Language Guide for both proto2 and proto3.

It might be a little confusing but proto2 doesn't correspond to v2.x and proto3 doesn't correspond to v3.x. Proto2 and proto3 are two proto language versions that are both supported in v3.x and some proto2 features are added in v3.x (e.g., map fields).