Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!purdue!gatech!prism!loligo!pepke
From: pepke@loligo.cc.fsu.edu (Eric Pepke)
Newsgroups: comp.sys.mac.programmer
Subject: Re: How do I read a line?
Message-ID: <751@loligo.cc.fsu.edu>
Date: 7 Jun 89 14:42:03 GMT
References: <10387@burdvax.PRC.Unisys.COM>
Reply-To: pepke@loligo.UUCP (Eric Pepke)
Organization: Supercomputer Computations Research Institute
Lines: 34

This is not really that hard to do, but you have to rethink the problem a
little bit.  Instead of thinking in terms of the program stopping and reading
input, where the program is in control, think in terms of the user deciding
when to give information to the program.  Have the program maintain an event
loop and a TextEdit window, just as you are doing.  Define a special key,
perhaps the Enter key or Command-Return that, when pressed, sends either
the selection range or the line that the insertion point is on to the program.
The program then uses a switchboard kind of approach to determine what to
do with the text; i.e. it asks itself "What question am I asking now?" and
applies the text to the answer.  Getting the selection range is easy, and
to get the line that the insertion point is on you can, for example, search
backward and forward for return characters and the beginning and end of text.

I have done something like this in a C program which contains a subset of
a Common LISP interpreter.  One of the windows is a LISP listener and forms
sort of an inside-out development system which is very handy.  My problem
is trickier, as LISP is not line-oriented, but the principle is the same.
(Instead of getting the line that the insertion point is on, I look back
and find where the last message from the program ended and read from there
to the insertion point.)

I am reluctant to give you all of the code, as it is quite a hack and I
don't bother, for example, to implement the Edit menu.  As David Dunham
says, if it doesn't have Undo, it's not a Mac program.  However, I will 
look at it to see if the relevant sections might be extracted and still
be meaningful.  Most of the rest is just TextEdit.

Eric Pepke                                     INTERNET: pepke@gw.scri.fsu.edu
Supercomputer Computations Research Institute  MFENET:   pepke@fsu
Florida State University                       SPAN:     scri::pepke
Tallahassee, FL 32306-4052                     BITNET:   pepke@fsu

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