[DB-SIG] dBase III and VFP tables

[Carl Karsten]

On Wed, Jul 20, 2011 at 11:33 AM, Ethan Furman <ethan at stoneleaf.us> wrote:
> as well as ignoring trailing white space for comparisons)

I wouldn't bother supporting that in the driver.

Another background lesson: dBase started as an interactive
environment. It didn't look like a spreadsheet, but think of a
spreadsheet: the typical use is to start typing stuff in by hand,
select some data with the mouse, hit sort,  select some numbers and
click Summation,  see the results on the screen.  At the time things
were still in the relm of teletype machines were the only thing you
looked at was printed output.  Screens were new, and the API was still
much like a printer.  (not exactly true, there was the EDIT command
that would clear the screen, draw field names and input boxes and let
you enter data and tab/back tab around the screen.)

It wasn't until later versions that they added the concept of
stringing a bunch of commands together.  conditionals came later.  A
design goal was syntax that is easy to type interactively, not make
sense in a formal programming language.    today we have "incremental
search" where as you type query parameters the search is executed and
you see results.  If typing "KAR" is all you need to figure out "CARL
KARSTEN" is the person you are looking for, then 3 keys are all you
need to press.  likewise, in dBase you could do
DISPLAY FOR LNAME="KAR"
and see just the rows where LNAME _begines with_ "KAR"  which makes
sense for an interactive environment, but causes grief when you try to
write programs.  later they added the == operator, but maintained
backwards computability with the _only compare until you run out of
chars_ behaviour.

_backwards computability_ is the only reason to implement this in the
driver, and given there is currenly no code relying on it, nothing
will break if you don't.  So don't :)

-- 
Carl K