snacktime
7/20/2007 4:44:00 AM
So today I finally had the time to sit down with racc and work on a
natural language for defining recurring billing cycles. The racc part
was actually pretty easy once I got a handle on how yacc works, but
it's the wording and syntax I'm struggling with a bit.
I'm trying to include most of the different billing scenario's that
I've seen used out there. The basic flow is that you have different
stages of a billing cycle. The first stage is what to do when a
customer first signs up. You can charge them immediately, charge them
in a number of days, or give them a free trial. Subsequent stages
define a billing cycle over a period of time. You can create several
stages where you can for example bill someone every month for 3
months, then bill them every 6 months for 3 years, etc..
What I'm having problems with is finding a way to use a similar syntax
to describe two different scenarios.
First we have the first stage which is something like this:
charge X amount now|charge X amount in 5 days|charge nothing now
Then we have subsequent stages:
THEN charge X amount every X day[s] for X times|until cancelled
So far so good. But here is another scenario that uses a different
syntax and could span the first two stages depending on how you look
at it.
charge $40 on the 1st of every month 12 times|until cancelled
In this scenario the first payment is usually prorated to whatever day
the billing cycle starts on. This example actually assumes a prorated
amount. I could also write it something like this, which would fit in
a bit better with the rest of the language syntax:
charge prorated amount now then charge $40 on the 1st of every month 12 times
I don't really like this last one, but it fits in better as far as how
stages are defined, where the first stage is always present and
defines how the first payment is handled.
Chris