Re: A Customer's Request For Open Source Software

["Warren W. Gay VE3WWG" <ve3wwg@cogeco.ca>]

Marin David Condic wrote:
> I agree that concurrency is difficult. What I'm talking about is that if 
> you built a core accounting engine that presented itself to the rest of 
> the application as an "object" and if that engine initially just 
> operated within RAM (load and store to a file), you'd have a useful 
> start. 
...
> MDC

Actually, that is not too far away! I just finished testing some generic
database code, that can swing between PostgreSQL and MySQL with just
a swap of a "with" statement in the main program (using APQ 2.0). This
relies heavily on tagged types and polymorphism, but it works very
well.

You build your code so that it only needs the database connection
Root_Connection_Type'Class (which naturally dispatches when used),
and the procedure that this connection object is passed to
can do everything else in a database neutral way.

This is not to say there aren't some database specific issues,
but there are ways to deal with most of these, and some of
them in a fairly generic way.

Since accounting is such a basic need, I have made plans to include
an accounting engine object in a child package, to do just the sort
of thing you have suggested. I mean, why build the accounting engine
more than once?  Everyone needs accounting. The package may
fit into the hierarchy structure as something like
APQ.Applications.Accounting. If you want to see a rough draft
of a PDF manual for APQ version 2.0, email me and I'll send it
to you (it includes some generic database code examples).

The first thing I had to conquer was generic database
programming, since I don't like being locked into one
brand of database.  Whatever I choose will be the wrong
choice for you, or the wrong choice 2 years from now.
But this annoyance is nearly out of the way now.

I only like to write such things once if possible, and
only support one instance of the same code. So the time is
now ripe for application objects of this type. It is nearly
next on my list of things to do, and I have a big list ;-)

-- 
Warren W. Gay VE3WWG
http://home.cogeco.ca/~ve3wwg