Re: [boost] RTL

From: Calum Grant (calum_at_[hidden])
Date: 2005-10-20 15:42:46

> > The solution I have is not terribly elegant from RML's 
> point of view, 
> > since as I said before RML is designed for logical queries 
> rather than 
> > numerical computation.  It was not a terribly interesting problem 
> > because it needed just a single table with two indexes.
> 
> Hmm, I managed to program it in RTL as a single relational 
> view on the original table, without doing _anything_ by hand. 
>  The correctness of this view is preseved by the library when 
> the data is changed.  In your case _you_ remove 1982 items.  
> In my case _the library_ removes 1982 items.  I think your 
> solution is rather by-hand than RML-based.
>
> Can you create a single RML query on the original table that 
> solves the problem?  Can you claim that using RML added a lot 
> to your solution?  Is it faster/more elegant/readable/etc.  
> than just using STL directly?

You make a very fair point.  This problem does not lend itself very well
to RML's queries.  RML's queries are much simpler, and therefore need to
be glued together with C++.  But even so, even these simple queries make
it easier to access data in the table, and the test was exercising the
library.  But my line-count was 243 lines, yours was 214, so it's not
such a huge difference.

I frankly have no idea how I would implement that problem in SQL, but
then this was a problem you chose to be very difficult to solve using a
SQL notation.  But that does not of course mean that SQL is a bad
approach for other things.  Even so, it is extremely interesting to see
how far one can take RTL's queries.  And it looks like considerable fun!

I would like to test a database-style application.  I feel RML's
notation and design would be much better suited to that type of problem.

Regards, Calum