Re: [using gcc book] ch1 objective-c blurb

[Ziemowit Laski <zlaski at apple dot com>]

On Monday, Aug 25, 2003, at 18:50 US/Pacific, Colin Douglas Howell 
wrote:

> Chris Devers wrote:
> > After splitting the text of _Using and Porting GCC_ into the 
> > _Using..._
> > and _Porting..._ books, the material remaining in _Using..._ is 
> > primarily
> > about C, C++, and Objective-C support. Chapter one, which is only a 
> > page
> > long, includes paragraphs about the first two language, but doesn't 
> > really
> > discuss the Objective-C aspect.
> > Based roughly on what is said about C++/G++, I've taken a stab at a
> > writeup of the ObjC side, but I'd like to be sure that what I'm saying
> > isn't wildly inaccurate.
> > For comparison, here's the existing G++ writeup:
> >     G++ is a compiler, not merely a preprocessor. G++ builds
> >     object code directly from your C++ program source. There
> >     is no intermediate C version of the program. (By contrast,
> >     for example, some other implementations use a program that
> >     generates a C program from your C++ source.) Avoiding an
> >     intermediate C representation of the program means that you
> >     get better object code, and better debugging information. The
> >     GNU debugger, GDB, works with this information in the object
> >     code to give you comprehensive C++ source-level editing
> >     capabilities (see section .C and C++. in Debugging with GDB).
> > Here's my ObjC paragraph:
> >     Compilation of Objective-C programs is done with GCC itself,
> >     rather than a front end like G++ or GNAT. As with G++
> >     programs, the lack of a preprocessor and the direct build
> >     of object code from your Objective-C program source provides
> >     better object code and better debugging capabilities.
> > Does this accurately reflect things? Is there anything else that 
> > should be
> > mentioned?
>
> My first thought about this is that while some discussion of Objective 
> C
> may be called for, the paragraph you propose above is completely 
> unnecessary.
> The manual mentions that G++ doesn't use a preprocessor because the 
> first
> popular C++ compiler, AT&T's CFRONT, actually *was* a preprocessor 
> which used
> the normal C compiler as the back end.  The GNU project wanted to 
> emphasize that
> G++ had a superior implementation.
>
> I admittedly don't know much about Objective C, but my impression is 
> that it
> never had a preprocessor-based implementation (in the CFRONT sense of 
> the term),
> so there is no particular reason to point out that our implementation 
> doesn't
> use one.

Actually, I believe there used to exist (and perhaps exists still?) a 
Stepstone
translator, which was precisely cfront-style technology. :-)


--Zem
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Ziemowit Laski                 1 Infinite Loop, MS 301-2K
Mac OS X Compiler Group        Cupertino, CA USA  95014-2083
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