rs4u#@ANDREW.CMU.EDU (Richard Siegel) (05/01/87)
Some questions:
1) Why the change? It seems to me that there's a large number
of programs that have the "Transfer" feature (as it's usually called),
that will suddenly stop working.
2) For Old Mac and Mac Plus owners (Old Mac = 64K ROM), does
this change come with System 4.x? Or is it simple a change in the ROM
for the SE and Mac II, so the "Transfer" feature will only crash
on the new machines?
3) *Flame On* Why is Apple doing this? I personally would simply
add another trap (_SubLaunch or somehting) to the 256K ROMs, or
make the existing _Launch trap smart enough to know when it's being
called with the old protocol, and adjust accordingly. As I said,
a lot of existing applications will suddenly stop working, and
there are going to be a lot of pissed-off users (not to mention developers!)
out there. I may not be looking at things realistically, but... *Flame Off*
4) By the way, will this interface change be backward compatible?
Suppose I fix the application to use the new interface. What if someone
runs it on an older System? Does it break then? Or will some way be
provided for the application to know which interface to use?
"I would advise people to wait the week or two for the
technote before implementing a lot of Launch code that
will have to be changed.
Great. 8-)
--Rich
Richard M. Siegel
Materials Characterization Instrumentation Section
Mail Stop 231
NASA/Langley Research Center
Hampton, Virginia 23665
(804) 865-3036
Arpanet: rs4u@andrew.cmu.edu
Uucp: {your fave gateway}!seismo!andrew.cmu.edu!rs4u
Disclaimer? I don't even KNOW 'er!lsr@apple.UUCP (Larry Rosenstein) (05/04/87)
In article <MUa8YYy00UhTQM00cm@andrew.cmu.edu> rs4u#@ANDREW.CMU.EDU (Richard Siegel) writes: > >Some questions: > > 1) Why the change? It seems to me that there's a large number >of programs that have the "Transfer" feature (as it's usually called), >that will suddenly stop working. Not likely. The sublaunch code simply adds a new feature to _Launch, it doesn't change anything else. The mechanism for passing additional parameters to _Launch was implemented in the 128K ROM, and as far as I know they have never been documented. In the 128K ROM, these extra parameters were used to indicate that a program should be launched read-only, which is useful if you are using a file server. > 2) For Old Mac and Mac Plus owners (Old Mac = 64K ROM), does >this change come with System 4.x? Or is it simple a change in the ROM >for the SE and Mac II, so the "Transfer" feature will only crash >on the new machines? The patch is definitely in System 4.1; I don't have a copy of System 4.0 around to see if it was in there as well. > 3) *Flame On* Why is Apple doing this? I personally would simply >add another trap (_SubLaunch or somehting) to the 256K ROMs, or >make the existing _Launch trap smart enough to know when it's being The new features are activated by a special signal to the _Launch trap. Normally, _Launch takes a pointer to a parameter block in A0. The first long of the block points to the file name and the next 2 bytes to the sound/screen page 2 options. If the 2 bytes after that is $4C43, then the extended parameter set is assumed. Following the code will be 4 bytes for the length of the extended parameters, followed by a word of flags. Bit 6 of the low flag byte is 1 to indicate a read-only launch. As I mentioned before, I don't have a copy of the new set of Tech Notes, which indicate how to specify a sublaunch. > 4) By the way, will this interface change be backward compatible? If the patch is not present, then the sublaunch will work, but (I assume that) the application doing the launching would not regain control. -- Larry Rosenstein Object Specialist Apple Computer AppleLink: Rosenstein1 UUCP: {sun, voder, nsc, mtxinu, dual}!apple!lsr CSNET: lsr@Apple.CSNET
huxham@apple.UUCP (05/06/87)
There were some misunderstadings resulting from my posting about _Launch so let me try and clarify. 1. Sublaunching is an extension to _Launch. Programs that call _Launch (transfer menus, etc...), will still work with System 4.1. 2. Sublaunching is available using System 4.1 or higher. 3. One application launching another however, is a discouraged practice. There are some applications that must do this (integrated development systems for example), but most applications don't need to. The reason for the discouragement is that at some point in the future (a year perhaps, the crystal ball I'm looking into isn't all that clear), _Launch MAY change or go away and everything that calls it will not work. The Finder is the application that should be used to launch applications. In the future, it may provide better integration for applications and you would circumvent this if you tried to take over its role by calling _Launch. _Launch will only go away if it is absolutely necessary. We don't break applications for fun. There will be heated discussions about it. But there may be a time when we have to make a decision between major improvements to the MacOS and breaking a few applications and we will choose to break apps. (We will however, give developers notice and a chance to change their products before the change takes place) Sorry for any confusion or panic I caused with my first posting, Fred