Path: utzoo!mnetor!uunet!portal!cup.portal.com!Andre_Louis_Marquis
From: Andre_Louis_Marquis@cup.portal.com
Newsgroups: comp.lang.c++
Subject: re: C++ Questions (Objective-C)
Message-ID: <2132@cup.portal.com>
Date: 23 Dec 87 17:27:52 GMT
References: <2054@cup.portal.com>
Organization: The Portal System (TM)
Lines: 53
XPortal-User-Id: 1.1001.3081


>We are investigating the differences between Objective-C and C++.

>What class libraries are available for C++?
Try getting a copy of Keith Gorlen's OOPS Library.  It is perhaps even larger
than the Objective-C library, and there's no copyright restriction.  OOPS is
in the "guru-only" stage, but I found it as easy to use and it's free.
Mr. Gorlen's uucp address is uunet!mimsy!elsie!nih-csl!keith.  Basically,
you send him a tape and he returns it with a copy of the library and some
preliminary documentation.  (And it's not printed on 8 1/2x6 1/2 yellow paper,
for those of you who know what I mean. :-)).  OOPS is bug free in my
experience, but it may not have been ported to as many machines as the
Objective-C library.  You do get all the source code, however.  I recommend
it if you don't mind a little adventure.  I'm using it for a major project.

>(I just requested information about Phoenix's PForce++.)
Would someone mail me a hint about this?  I'm new to this conference.

>If I define a common superclass for all objects (Object), as
>others have mentioned, do I get the flexibility that Objective-C provides?
>Are there any problems with that strategy?  Since C++ doesn't provide this
>capability directly, it seems to conflict with C++'s underlying philosophy.
OOPS defines a common class hierarchy.  You may test object classes and
phyla.  Virtual methods are inherited and can be overridden.

>Is there any equivalent of [super foo] in C++?  This allows method foo to
>invoke the inherited method that was overridden.
You just scope the name -- super_class::foo().

>Are there any fundamental differences between the messagers, or is that
>simply an implementation issue?
There is no dynamic messaging in C++, i.e. no "perform: selector" message, but
normal messaging is faster.  You also get automatic constructors/destructors,
operator redefinition (<< and >> I/O is nice) and a more general paradigm.

(On the hustings he goes...)
But, most of all, C++ is a powerful, multi-vendor standard.  There are
free toolkits (OOPS for classes, InterViews for X Windows, ...?) and soon a
free compiler and debugger. (Thank you, Michael Tiemann and the Free Software
Foundation.)

I think that PPI has done some very good work with Objective-C.  They also
charge a hefty fee for it (An ICpak (It's user interface software.)
development license is $35,000 + $5,000 for the source code, for example.
I'm sure it's excellent stuff, but $40K is STEEP.)  You rely on them for
innovation and bug fixes.  (In addition, I think their documentation is
horrible.  Correct me if I'm wrong.  Their manual has ONE complete example
program.  Stroustrup's book is in a different league.)  There are people who
are glad to do the same manner of hand holding for you with C++ that PPI
provides for Objective-C.

I've used both and I prefer C++.  That's an opinion.

Andre Marquis