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Avro, mail # user - Best practices for java enums...?


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Re: Best practices for java enums...?
Jeremy Kahn 2013-05-10, 18:47
+1 to this suggestion. Docs on individual symbols in IDL enums would be
convenient.

Felix, will you file that ticket please? I can promise to upvote.
On Fri, May 10, 2013 at 10:55 AM, Doug Cutting <[EMAIL PROTECTED]> wrote:

> If you use Avro IDL then you can more easily maintain long, multi-line
> comments for your enum.
>
> http://avro.apache.org/docs/current/idl.html#minutiae_comments
>
> IDL files (.avdl) can be compiled to Schemas (.avsc) by Maven, which
> are then compiled to Java.
>
> Documentation per enum symbol is not currently supported, but would
> not be difficult to add.  Please file an issue in Jira if you'd like
> to see this.  For compatibility, in Json, this would probably appear
> as a parallel array of documentation strings, e.g., something like:
>
> ("name": "Foo", "type":"enum", "doc":"an enum", "symbols":["X","Y"],
> "symbols-doc":["X is X", "Y is Y"]}
>
> Doug
>
> On Thu, May 9, 2013 at 4:39 PM, Felix GV <[EMAIL PROTECTED]> wrote:
> > Hello,
> >
> > I'm currently writing an avro schema which includes an enum field that I
> > already have as a java enum in my application.
> >
> > At first, I named the avro field with the same fully qualified name
> (package
> > name dot enum name) as my existing java enum. I then ran the avro
> compiler
> > and found that it overwrote my existing java enum with an avro-generated
> > enum.
> >
> > I find this slightly annoying because my java enum had comments
> documenting
> > the purpose of each enum value, and the avro-generated enum doesn't have
> > this.
> >
> > I see two or three potential solutions:
> >
> > Accepting to replace my current enum with the avro-generated one in my
> code
> > base, which I feel I cannot document properly (since I have access to
> just
> > one doc attribute for the whole enum, instead of per symbol). On a side
> > note, I haven't found any way to have a multi-line doc attribute in an
> avro
> > schema, so that makes things slightly more annoying still. I wouldn't
> mind
> > settling on using the avro-generated enums without documentation per
> symbol
> > if at least I could have one big doc/comment that documents all symbols
> at
> > once, but since it seems the doc attribute must be a one-liner, this is
> > starting to be a little too messy for my taste...
> > Maintaining two separate enums: my manually written (and documented)
> enum as
> > well as the avro-generated enum. For now, I think this is what I'm going
> to
> > do, because those enums have little chances of changing anyway, but from
> a
> > maintenance standpoint, it seems pretty horrendous...
> > I guess there's a third way, which would involve creating a script that
> > backs up my enums, compiles all my schemas, and then restores my backed
> up
> > enums, but this also seems ultra messy :( ... I haven't tested if it'd
> work
> > (since the manually written enum is missing the $SCHEMA field), but I
> guess
> > it would...
> >
> > Am I being OCD about this? or is this a concern that others have bumped
> > into? How do you guys deal with this? Did I miss anything in the way avro
> > works?
> >
> > P.S.: I've seen that reflect mappings may be able to work with arbitrary
> > java enums, but since they seemed discouraged for performance reasons, I
> > haven't digged much in this direction. I'd like to keep using .avsc
> files if
> > possible, but if there's a better way, I can certainly try it.
> >
> > P.P.S.: We're currently using avro 1.6.1, but if the latest version
> provides
> > a nice way of handling my use case, then I guess I could get us to
> > upgrade...
> >
> > Thanks a lot :) !
> >
> > --
> > Felix
>