Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!mitch
From: mitch@Apple.COM (Mitchell Adler)
Newsgroups: comp.sys.mac.programmer
Subject: Re: MPW cmd language
Keywords: MPW
Message-ID: <32774@apple.Apple.COM>
Date: 29 Jun 89 00:14:00 GMT
References: <495@unicads.UUCP> <919@iraun1.ira.uka.de>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 52

In article <919@iraun1.ira.uka.de> norbert@ira.uka.de (Norbert Lindenberg) writes:
>In article <495@unicads.UUCP> tom@unicads.UUCP (Tom Gerardy) writes:
>>I am trying to put up ctags and a vi/tags like facility in MPW (actually
>>it is already working.)  The output of the tag tool is a string of MPW
>>commands to open the file and find the search string.
>>...
>>Currently I am having to write the output to a file and execute it as
>>a script.  This seems to slow things down considerably since both "open"
>>and "find" are builtins.
>I developed a similar package for MPW Pascal some time ago
>(LookupDeclaration, available from the info-mac archives),
>and also could not find a better way. Probably there is none...

There is a different way, but depending on the complexity of the
script producing the script to execute, it is a little messy...

The trick is to use back-quotes (`) to put your standard output on the command
line. If it happens that your output is executable, it will be executed, i.e.

`getListItem 'files -l' files; files -t TEXT`

will let you choose the command to execute on all the text files in the current
directory. Since back-quotes just put text on the command lines, that text can
be anything you want it to be, even a command (or series of commands) to
execute.

One thing to rember is that the syntax for back-quotes allows *any* script to
be executed (even looping structures, begin/ends and the like), BUT the whole
script must be on one "line", that is there must be no carriage returns between
the start and end back-quotes that aren't masked with option-d's.

Not having cirrage returns means adding semi-colons between all your commands,
more dirt, it can get really messy, but sometimes it is truly elegant.

And the final problem is that you are already inside a set of back-quotes so
if any of your commands need to use back-quotes in their command lines, you
need to escape them (with option-d).

In my experience it is valuable to use this trick whenever it will help you
avoid creating a temporary file without adding more than 20 option-d's :-).

For those real purists out there, this trick won't avoid creating a file, MPW
uses temporary files to do back-quoting, but it does put the problem of naming
and deleting the temprary file back in MPW's hands (where it should be).


Mitch Adler                      "Hamper? ... I have a Hamper?"
Apple Computer                                    - Dr. Peter Venkman

mitch@apple.com                  "Prepare for jump to...ludicrous speed!"
AppleLink: M.ADLER                                - Dark Helmet