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From: omh@cs.brown.edu (Owen M. Hartnett)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Question About Lists....
Message-ID: <79696@brunix.UUCP>
Date: 29 Jun 91 02:29:55 GMT
References: <1991Jun24.231936.15327@cis.ohio-state.edu> <14272@goofy.Apple.COM>
Sender: news@brunix.UUCP
Reply-To: omh@cs.brown.edu (Owen M. Hartnett)
Organization: Brown University Department of Computer Science
Lines: 54

In article <14272@goofy.Apple.COM> rmh@apple.com (Rick Holzgrafe) writes:
>In article <1991Jun24.231936.15327@cis.ohio-state.edu> 
>rubin@cis.ohio-state.edu (daniel j rubin) writes:
>> I want to write a application that will display all the items in a file 
>on
>> the hard drive using the list manager ( I think ).  The database can 
>have 
>> 10000+ records [...] I read that you cannot 
>> create a list with more than 32K of data.
>
>True enough, but you don't have to keep all the data in the List Manager's 
>records. By writing a custom LDEF (very easy to do), you can simply keep 
>pointers (or handles, or array indexes, or whatever) in the list, and have 
>your LDEF use the pointers to access and display the real data kept 
>elsewhere.
>
No, No, Don't put anything in the List Manager's data, that's the key!
Your LDEF gets the number of the cell it needs, you use that number to
index into your own data and draw it into the rect that the LDEF also gets.

>Nevertheless, 10000+ records is really pushing the limits of the List 
>Manager. You could do it if the list contained (say) 16-bit array indexes, 
>but I bet it'll be slow. The List Manager was designed as a simple, 
>standard way to present simple, reasonably small lists; it wasn't intended 
>to be the perfect front end for a major database engine.
>
10,000 records isn't bad, I've done it with >18,000 records with no problems
and response was indistinguishable from a 50 record list.  Keep your
data out of the List manager, and just use the List Manager routines to
manage the interface.

>What the List Manager does isn't that complicated. Consider writing your 
>own solution, tailored to your needs. (And while you're at it, give a 
>little thought to different interfaces altogether. Obviously I don't know 
>the details of your needs, but I for one wouldn't enjoy scrolling through 
>10000+ records, trying to find the one I want...)
>

You don't have to roll your own, if you do what I've said.  Practically
speaking, you'll also need an additional way to display desired records,
such as typing the beginning of the search key and have it scroll to the
first match found.

Please no flames on a 10000 record scrolling list.  I've researched it
pretty well and have determined that it was the most workable way and
the implementation actually works better than you would think.

-Owen


Owen Hartnett				omh@cs.brown.edu
"FAITH, n. Belief without evidence in what is told by one who speaks
		without knowledge, of things without parallel."
			-Ambrose Bierce - The Devil's Dictionary