From: Kevin Howe <kh@...>
Date: 2005-02-04T11:55:39+09:00
Subject: Re: [ANN] LXL (Like Excel) 0.1.0 - A mini-language that mimics Microsoft Excel formulas.

> Pretty interesting. So why did you write this? Did you have particular
> applications in mind? Would LXL be suitable for, say, exporting the
> logic in an advanced Excel spreadsheet into something in Ruby?

> Pretty interesting. So why did you write this? Did you have particular
> applications in mind? Would LXL be suitable for, say, exporting the
> logic in an advanced Excel spreadsheet into something in Ruby?

Hi Francis,

I developed it to allow customer-defined workflow rules for their web system
(an HR/Purchasing system). For instance, when a purchase order is submitted,
different things happen depending on:

- what office is was submitted from
- what employee submitted it
- what permissions the employee has
- the amount of the purchase order
- the type of the purchase (bi-weekly/monthly, office supplies/consumables)
- etc.

Rules are applied to these criteria to decide what happens next:

- are they over budget by more than $1000? Deny it.
- are they under budget by more than $500? Approve it.
- if submitted from head office, submit to a supervisor for approval.
- etc.

These rules were hard coded at first just to get things going, but these
factors are constanly in flux so they needed to be controlled at the
user-level. Ex: Last month those rules were fine, but this month one of the
offices needs to be able to purchase without a limit, another office needs
to be auto-approved for office supply purchases, but still limited for all
other purchases. A supervisor has gone on vacation for two weeks, and for
that period all approval requests should be sent to another supervisor
instead. The kinds of rule-changes are constantly happenning and need to be
put into effect immediately - they can't be calling an IT person for every
change. The solution was to allow them to program these rules themselves,
using a limited but user-friendly language. Excel formulas were the ideal
choice in this case because the entire company is already intimately
familiar with what they are and how they work. LXL provides the basic
language, the parsing and the basic functions (math operators, if/and/or
conditionals, date/time, etc). Then you extend it with your own custom
constant values and functions. You might have something like
IF(AND(OFFICE="HQ",REMAINING_BUDGET<500)) for instance.

That's the general idea ;)

Regards,
Kevin