C++ vs Objective-C Comparison Study

[Tom Mackey]

I have been hearing rumors regarding a C++ vs Objective-C discussion
on the net.  I have been watching net.lang and net.lang.st80, but
finally found some reference to the two languages on net.lang.c.  I
think a net.lang.c++ may someday be in order.  To get to the point,
we here at Burroughs DSG have used both languages in our current
(very large) software development.  We started out with Objective-C,
but switched to C++ when it became available to us.  What follows is
an encapsulated comparison study written by my manager, who has
asked me to post this.  Since Gary is usually too busy to read
either E-mail or net news, please reply directly to me, and I will
dump a hard copy and put it on his chair (the only sure way to
contact him :-) ).  I was involved in the study, and therefore could
answer any questions you might have.  Of the present staff, I have
written more Objective-C code than anyone else, and re-wrote almost
all of that in C++.  Just to give you an idea of the similarities, I
re-coded my approx. 2000 lines of debugged Objective-C code into
C++ in about 2 weeks time...that is taking time out for some
extensive re-designing, so I can't say exactly how many lines of C++
corrosponds to how many lines of Objective-C.  If there is enough
interest, however, I can do that with a doubly-linked-circular list
object class that I wrote in both languages.

So without further ado, I give you Gary's study, enclosed in the
dashed lines, and followed by my net address.  I am posting this to
net.lang, net.lang.c, and net.lang.st80; please direct all followups
to net.lang.c.  Thanks,        -Tom M.-

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Subject:  Objective-C vs. C++ Comparison Study

    We did an Objective-C vs. C++ comparison study at Burroughs
Distributed Systems Group, Boulder Colorado, covering the following 
areas:

    1. Ease of use/learnability.
    2. Development time.
    3. Execution speed.
    4. Code/data size.
    5. Maintainability.

    Both Objective-C and C++ offer data abstraction features with
classes, objects, and inheritance;  Objective-C following the Smalltalk
syntax and C++ more closely modeled to Simula.  Both language
implementations are really "translators" that sit between the "C"
pre-processor and the "C" compiler for the particular system--both
take source code and generate "good old C" code for compilation,
so portability to different processors is excellent.  In addition,
object code generated from C++ is link-compatible with object code
from "good old C";  in fact, C++ is a superset extensions of C
(to the point where it will compile a C program just fine, thank-you),
while Objective-C is not.

    We wrote programs implementing the same functionality and made
measurements that were both objective and subjective in nature
on System 5.2 UNIX running on VAX 11/750s and 11/780s.  By "objective"
we mean that system performance measuring commands such as "time"
and "size" were used;  by "subjective" we also recorded our feelings
as to how comfortable we felt with the language, etc.

    It was our conclusion that C++ significantly beat Objective-C in every
category.  For some categories, such as execution speed and code/data
size, this is not surprising--C++ is wonderfully efficient.  However,
one might have expected development and maintainability to have fared
better with Objective-C.  Compilations using Objective-C took in some cases 
two to three times longer than C++ compilations for similar programs.
Yet, because Objective-C employs an artificial file dependence called 
"phyla" to speed up the execution performance, we felt in the end that 
we were left with a less maintainable product using Objective-C than 
with C++.  Our people found the creation and maintenance of phyla 
dependencies unnatural, awkward, and very time-consuming to recompile.
It seemed to us that Objective-C tried to offer maintainability with
classes with one hand and usurped it all (and more) by requiring phyla 
with the other hand.  Yes, this is harsh criticism for a package that
claims to offer the prospect of more reliable software products, but
these were our conclusions.

    Objective-C, in its favor, does offer a very nice run-time library
of handy classes for "containers", filing, and debugging.  These
library capabilities are not always useful or desireable, however;
it depends on your application and intended usage.  C++
comes with a smaller "general library" of classes but is easily
extended and can be used with "sdb" with less fuss. 


Gary Walker, Manager, Primary Interaction Development
Burroughs Distributed Systems Group
6655 Lookout Road
Boulder, Colorado  80301
(303)-530-6754

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Tom Mackey   						hao!\
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Burroughs Distributed Systems Group 		     Boulder, Colorado