Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hplabs!hp-pcd!hplsla!jima
From: jima@hplsla.HP.COM (Jim Adcock)
Newsgroups: comp.lang.c++
Subject: Re: Objective C: Flame Fodder
Message-ID: <6590109@hplsla.HP.COM>
Date: 28 Apr 89 17:19:14 GMT
References: <5007@tekgvs.LABS.TEK.COM>
Organization: HP Lake Stevens, WA
Lines: 70

> In article <6590099@hplsla.HP.COM> jima@hplsla.HP.COM (Jim Adcock) writes:
> > ...
> >To me, C++ is object-oriented, and ObjC isn't.
> > ...
> 
> From my understanding of Obj-C (from reading Brad Cox's "Object Oriented
> Programming"), there is no reason you can't add the [] messages to C++,
> getting Objective-C++. Then you have the best (and worst) of both worlds.
> [p.s. IMHO Obj-C is more like Smalltalk so "objected-oriented" but that
>       is by-the-by] ... cheers, matt.

Well, as one who comes from an ObjC enviroment, with on the order of 100
man-years invested by my local organization in ObjC, many people here have
certainly entertained the thought.

And the answer is, practically speaking, you cannot do it.

ObjC is a compiler that accepts straight-C plus 
ObjC [myObject with: junk andmore: junk]
syntax for messaging and "compiles" the result to straight-C code.

C++ is a compiler that accepts straight-C plus C++ extensions
to the syntax.

Neither accepts the other's extensions to C syntax.  So to run
one into the other you'd be restricted to using the straight-C
common subset used by both langauges.  If you're lucky.  In
which case you've gain nothing.

My answer was to try to salvage ObjC code [where ObjC development
gave us something actually reuseable] by writing a translation
aid that turns ObjC's:

[myObject with: junk andmore: junk]

into a C++

myObject->with_andmore(junk, junk)

[in real-world examples the name translation usually comes out prettier
 than this :-]

To perform this translation reliably, you have to parse the language,
textual substitution doesn't hack it.  So the translation aid ends up
looking a lot like the front end of a full compiler.  Except my 
translator [at least] doesn't understand the semantics, typing, etc
of objects, so the translator only saves maybe 90% of the effort
one would have to put into a totally manual translation effort.

Initially, coming from an ObjC environment, I felt:

[myObject dosomethingwith: this and: that]

was a prettier syntax than C++'s

myObject->dosomething(this, that)

but ObjC programmers [hackers?] write a lot of code like:

[myObject dosomethingwith: this and: that and: thenextthing and: more and: more and: more]

which really isn't object oriented programming -- its really functional programming.

C++ syntax, and low messaging cost, encourages programmers to only use zero, one
or two parameters to a method.  So in C++, you "set up" your object, then ask it
to perform a task based on its state, rather than passing in everything as a parameter.

And the C++ syntax is proving to be much more flexible.  People are taking C++
in an incredible variety of directions -- and for the vast majority of cases,
C++ syntax is up to the job.