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From Michael McCandless <>
Subject Re: FunctionValues vs DoubleValuesSource
Date Thu, 12 Oct 2017 22:25:36 GMT
Hi Mike,

It looks like FunctionValues is a very old API used by many function
queries, while DoubleValuesSource is relatively new (introduced in

This comment (
on the issue seems to refer to wrapper classes to convert between the old
and new APIs?

I admit the situation is rather confusing; but we've been gradually working
on cutting over modules to the new API.  Patches welcome!

Mike McCandless

On Tue, Oct 10, 2017 at 3:39 PM, Sokolov, Michael <>

> Hi, I'm trying to implement a complex set of values computed according to
> some externally-driven specification, so I am looking at these APIs. My
> question is whether there is any way to mix them. I have implemented some
> DoubleValuesSources and now I want combine them using sum, max, etc. I
> noticed these handy classes over in o.a.l.queries.function.valuesource,
> but they seem to be of a different flavor than the DVS API is designed for.
> EG DVS is kind of an iterative API while the functions appear to be random
> access (you pass them a docid). I could code up my own DVS for functions
> like max, sum and so on, but I wonder if there is some kind of adapter, or
> at least a reasonable strategy that would let one mix these apis?
> -Mike
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