> Why is it that neither MacOS, any form of Windows, or any commerical Unix
> I have seen has any kind of decent system for managing installed software
> and handling upgrades? Red Hat and Debian Linux demonstrate that such a
> thing is perfectly possible, and not even particularly hard to implement.
> It's amazing what making the operating system and most of the software
> free and having competition for distributions of it can do...
>
> Elsewhere we have Microstuft controlling the playing field -- and
> moving the goalposts regularly -- and not particularly keen on making
> installation of anyone else's software easy.
Good point. But! There is an inherent weakness in all installation
mechanisms I've seen where the O/S relies on dynamic libs.
1. On Unix, an application install generally does NOT overwrite
crucial system-wide DLLs, like the shared C libs, kernel libs.
This of course would wreak the havoc mentioned by the original
post re: MVS. And of course, if you are not installing as
root, you cannot overwrite the crucial files anyway.
2. On Windows, an application CAN install over top of crucial
system DLLs. We all live with the consequences: suddenly,
encryuption no longer works, or some aspect of the Windows
visual controls (3D controls are a good example) stops working.
The real culprit here is older installs that blithely replace
new DLLs with old.
BTW: almost EVERY invocation of "Remove Programs" that I have
run under Win95 does an incomplete uninstall, and reports:
"Some programs or files were not removed. Please refer
to the appropriate documentation and do it yourself..."
or something ot that effect. Yah, right. I must be stupid
or I don't know what ... never been able to comply with that one ;-)
3. On MacOS, these are called extensions, with a system default
installed at system creation creation time. Applications may
add to system-wide extensions, but cannot edit the already-
installed base of extensions. [Actually is it possible, but
this is verbotten for Mac programmers - and is never done.]
Richard Welykochy
Dot Communications Ltd tel: (02) 9281 1111
Level 19, 323 Castlereagh St fax: (02) 9281 2219
Sydney NSW 2000