From: Caleb Clausen <vikkous@...>
Date: 2006-07-24T11:12:20+09:00
Subject: Re: Mongoose 0.2.0

On 7/23/06, Jamey Cribbs <jcribbs@netpromi.com> wrote:
> No, it looks like I will have to go back to doing a yield in Table.find,
> which means the user is going to have to specify a block parameter in
> the #find block.  In other words:
>
> Employee.find { |emp| emp.dept == @dept }
>
> I guess it doesn't look that bad.

Ok, this is a totally different sort of query language, but have you
considered something like Reg? (http://rubyforge.org/projects/reg/ or
gem install reg) I took a more declarative approach (at least, I think
so) to a query languange, which (IMNSHO) is a better fit with the
problem. Reg is entirely based off #===, so all you'd need to do is
allow your find to take a parameter which responds to #===. That would
make the above example look like:

   Employee.find(item_that.dept==@dept)

or alternately:

   Employee.find(-{:dept=>@dept})

This should solve your problem with instance variable visibility in
blocks, since there are no blocks, but does it create other problems?
I don't know.

Reg is entirely designed from the point of view of queries on
in-memory Ruby object trees, so that's a little different than a
database model. But maybe you can get some ideas if nothing else...

I don't know anything about skiplists or database query optimization,
but Reg expressions look like nicely parsed trees of objects, so that
ought to be something you can work with...