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From Simon Willnauer <>
Subject Re: [lucy-dev] FieldType: no default properties
Date Wed, 22 Sep 2010 06:23:29 GMT
On Wed, Sep 22, 2010 at 2:39 AM, Marvin Humphrey <> wrote:
> On Tue, Sep 21, 2010 at 07:17:20PM +0200, Simon Willnauer wrote:
>> I don't know if that is a really good usecase for flags integers though. For
>> something high level as FieldType I would guess there is more than just
>> boolean flags - maybe not now but in the future.
> I think we agree in that the constructors for FieldType subclasses (such as
> TextType) will have to take more than just a flags integer.  For instance,
> TextType's constructor has to take an Analyzer, and I think it should take a
> Similarity as well.
>    TextType*
>    TextType_new(Analyzer *analyzer, Similarity *similarity, uint32_t flags);
> However, we do have to bear in mind that in C, we don't have signature-based
> overloading or optional parameters -- so every time we add a new parameter to
> the constructor, the C API will have a compat break.  That's acceptable under
> our "unstable trunk" policy, but it's not desirable.
> A flags integer allows us to add new boolean properties (so long as they can
> default to false) without breaking back compat on the C API, up until we run
> out of flag bits.  It's also highly idiomatic C, and it translates easily to
> the named parameters we'd use in Perl, Python, Ruby, etc.

Yeah I guess you have a point here. I was thinking to restricted in
what you where proposing, seeing the TextType "ctor" up there clears
things up.
>> I have a whole bunch of ideas for FieldType since I work on something
>> similar in lucene land and I am happy to share those ideas.
> What did you have in mind?  I know of
> <>, but I didn't see you
> there.

This is the issue where its started yet there is an impl but its not
up there. Stay tuned.
>> While I see your point I think we should not try to maintain bw compat
>> to kino search. I had the impression that this is a fresh start please
>> correct me if I am wrong. If we maintain BW compat (what a pain man!)
>> then +1
> This would be index file-format compat only.  API compatibility is impossible
> because of the namespace change from KinoSearch to Lucy.
> I'm not wedded to the idea of maintaining compat -- it just seemed like the
> obvious thing to do.  Releasing early and often was a fundamental goal we set
> for ourselves in our incubation proposal.  Making Lucy read KinoSearch indexes
> wouldn't be that hard unless we get really ambitious between code import and
> the first release.
> Deprecating KinoSearch is easier if we can provide a clear migration path for
> KinoSearch's users.  Here at Eventful, we have several dozen multi-gigabyte,
> fast-moving indexes; I'm sure you can understand why it would be nice for us
> to just switch in some code based on Lucy, restart the apps, and declare
> migration done. :)  If that's not to be, it's not to be, and we'll just deal
> with it.  However, the sooner that Lucy can persuade KinoSearch's users to
> switch, the better off we'll be.
>> Are we already that far to talk about something like Field Type?
> FieldType is already deeply embedded in the codebase.  Unlike Lucene, we
> already have per-index field-name-to-field-type associations.
That is what I mean - we have nothing right now since we haven't even
imported stuff. It pretty hard for me to follow since I don't even
know which code you are talking about :)

I will just hold off until the import is done.

> Marvin Humphrey

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