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Avro >> mail # user >> Doc strings in IDL not working

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Re: Doc strings in IDL not working
On 9/1/11 10:34 AM, "George Fletcher" <[EMAIL PROTECTED]> wrote:

>  Hi,
>  I'm trying to use the velocity templates to extract doc strings from the IDL
> using my own SpecificCompiler.  The IDL file looks like this...
>  /** class=@AccessControl(group="normal") */
>  @namespace("com.aol.interfaces.echo")
>  protocol EchoService {
>      import idl "Errors.avdl";
>      /** Message structure for the echo service */
>      record Message {
>          /** the string to be echo'd */
>          string echome;
>          map<string> echoes;
>      }
>      /** method=@AccessControl(source="MyService") */
>      string echoString(string msg) throws
> com.aol.interfaces.error.ServiceError;
>      Message echoMessage(Message msg) throws
> com.aol.interfaces.error.ServiceError;
>      void publishMessage(string msg) oneway;
>  }
>  I expected based on AVRO-296 (https://issues.apache.org/jira/browse/AVRO-296)
> being part of 1.5.1 that I should be able to get the doc strings from the
> parsed IDL. However, this doesn't appear to be working. In looking at the
> source code, it appears that doc strings are only saved for Enum, Fixed and
> Schema.

According to the Avro Specification, only Enum, Fixed, and Record are named
types that can have a 'doc' field in the Schema.

Can you open a ticket to discuss adding doc support for other schema types,
and list out some use cases?  Supporting doc for all types has some
implementation complexities, which is why it is currently only valid on
named types.  For unnamed types, it is arguably a bug that you can set a
property named 'doc' in the schema for unnamed types, but the spec is not

>  Given that doc strings are supported for Schemas, I expected to see the
> 'Message structure for the echo service' in my generated java code. However,
> even with the default velocity templates this string isn't present in the
> generated files.

Supporting a use case where documentation from IDL -> Java code persists is
different than supporting 'doc' fields in the schema in general for all
types.  Is this the most important use case?

>  Has any else run into this? Do I just have some simple syntax error in my
> IDL? Is there are reason that the parser doesn't support doc strings for more
> of the types? (e.g. Messages?)
>  Thanks,
>  George