inclusive-lower-bound, exclusive-upper-bound (was Re: Range Operation pre-PEP)

[Andrew Maizels]

Aahz Maruch wrote:
> 
> In article <3AFC5DF2.AB13724C at one.net.au>,
> Andrew Maizels  <andrew at one.net.au> wrote:
> >
> >For example, I like Python's use of new-line as a statement separator,
> >but in Pixy you can embed relational database queries directly into your
> >code, and given the target application domain (business applications
> >like accounting, customer service etc), I expect they'll be one of the
> >commonest constructs in Pixy programs.  Unfortunately, queries have a
> >tendency to be quite lengthy, and trying to squash them into one line or
> >having line-contination markers all over the place both seem like bad
> >ideas.
> 
> That's why Python has triple quotes.

Sorry, I wasn't quite clear: these queries are part of the language, not
embedded SQL.

So, if I have an accounts database with customer records containing
name, address, account balance etc, and item records containing date,
due data, amount, open amount, customer number etc, and I wanted to send
a letter to every customer with a balance of more than $50 over 60 days,
I could write something like:

    open database accounts for read.
    import send_polite_email, send_polite_letter from send_letter.

    var c, i are buffer.
    var over60 is decimal.

    for c in customer
    where c.balance <= 50:
        -- can safely ignore customers with balance <= $50

        over60 := 0.

        for i in item
        where i.custnum = c.custnum and
              i.duedate < today - 60 and
              i.open <> 0:
            over60 += i.open.
        end.

        if over60 > 50 then do:
            if c.email <> ""
            then send_polite_email(c.email,c.name,c.balance,over60).
            else send_polite_letter(c.address,c.name,c.balance,over60).
        end.
    end.


Pixy's syntax is still in flux, but that will give you the idea.

Andrew.
-- 
There's only one game in town.
You can't win.
You can't break even.
You can't quit the game.		-- The four laws of thermodynamics.