Re: Business objects, subset of collection

By the way, what is your RAD IDE of choice?
For the last 20 years before retiring I was an R-T/E guy so the only RAD
problems we saw were support tools for the software process (e.g.,
defect tracking). For that mundane stuff I usually used Access. I
haven't looked at the market so I wouldn't know what to use for
something like a web-based POS where one has both networking and server
issues. (There wasn't much around back in the '70s when I was doing IT,
but I'm sure we've come a long way since.)

When you say "When I need to solve a CRUD/USER problem I forget about
OO and use a RAD IDE", you are talking about MS Access? Since you
frequently refer to RAD IDE as the silver bullet for everything that
the OO model can't solve, it is a little big surprisingly that the
only RAD IDE you have experience from is MS Access. Don't you think
there are something between the OO approach and MS Access?

To clarify, when I refer to RAD IDE I also include the object-based
"canned" infrastructures in things like .NET and J2EE that support the
1D Presentation/Business/Data models. Those are certainly between Access
and an OO development.

In what way does J2EE support 1D Presentation/Business/Data?

create view invoice_balance as
select i.invoiceid, i.amount - sum(p.amount)
from payment p
join invoice i on i.invoiceid=p.invoiceid
group by i.invoiceid

How is this different than a VBA routine tied to a predefined event in
Access and stored by Access for reuse?

If you show the VBA routine, I can tell the difference...

The great thing with views is the fact that you can reuse this piece
of relational algebra. Lets say I want to find all over due, unpaid
invoices for creating reminders.

select i.invoiceid
from invoice i join invoice_balance ib on i.invoiceid=ib.invoiceid
where ib.balance > 0 and datediff(now(), i.duedate) >= 10

How would your solution look like? Collection with all over due
invoices automatically updated every 24 hour?

The VBA syntax will be very
similar since it is designed (i.e., has specialized constructs) to be
compatible with and easily converted to SQL.

Are you saying that Visual Basic and SQL has similar syntax? If yes,
please show it to me.

Using such view, you call "select balance from invoice_balance where
invoiceid=?", whereever in your application, reusing the business
logic above.

I am missing the point. This seems like basic modularization that goes
bas to function libraries under SA/D/P. Different development
environments will have different mechanisms, but they all do the same
thing. (The OOP-based agile processes argue that the primary goal of
refactoring is to eliminate code duplication and ensure reuse.)

Yes, you almost got it. Views corresponds to functions or classes. It
is all about modularization.

//frebe
.

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