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From: tim@hoptoad.UUCP
Newsgroups: comp.sys.mac
Subject: Re: HyperCard Availability
Message-ID: <2852@hoptoad.uucp>
Date: Tue, 1-Sep-87 01:02:45 EDT
Article-I.D.: hoptoad.2852
Posted: Tue Sep  1 01:02:45 1987
Date-Received: Wed, 2-Sep-87 06:37:41 EDT
References: <641@noao.UUCP> <133@stech.UUCP> <3703@sdcsvax.UCSD.EDU> <2829@hoptoad.uucp> <3841@well.UUCP>
Reply-To: tim@hoptoad.UUCP (Tim Maroney)
Organization: Centram Systems, Berkeley
Lines: 32

In article <3841@well.UUCP> alcmist@well.UUCP (Frederick Wamsley) writes:
>I thought the absence of data structures in Hypertalk was a serious problem
>until one of my coworkers pointed out that a card is a structure, with
>individually addressable fields.
>-- 
>Fred Wamsley  {dual,hplabs}!well!alcmist;well!alcmist@lll-crg.arpa;
>CIS 72247,3130; GEnie FKWAMSLEY;ATT Mail fwamsley; other uucp 
>uw-beaver!uw-june!bcsaic!asymet!fred; USPS - why bother?

Yes and no.  First, fields are the HyperCard objects I have the most trouble
with; it doesn't seem to be possible to use "target" in handling messages to
them, passing them actually passes the text so that resetting them doesn't
do anything globally, and if they are used in a "structured" hidden way,
then you have to put in utility scripts to deal with them conveniently.

Second, it is often neccessary to impose more structure than a per-card
structure.  For instance, suppose you have a number of polygons in a card.
Each polygon is stored as a hidden field that has a list of the corners, one
per line, in x,y (item) format.  So then you can get point n by saying "line
n of field f", and the x of that by saying "item 1 of line n of field f".
What you have are not data structures, but arrays.  Much less powerful, much
less readable, much less maintainable.

You can build data structures on top of arrays, but I wouldn't place any
bets on the performance of an *interpreted* system using such techniques.

What is really needed is an addition of real data structures to the
language.  I think a form letter metaphor would work quite well and be true
to Apple's design goals.
-- 
Tim Maroney, {ihnp4,sun,well,ptsfa,lll-crg,frog}!hoptoad!tim (uucp)
hoptoad!tim@lll-crg (arpa)