Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!crdgw1!uunet!taumet!steve
From: steve@taumet.com (Stephen Clamage)
Newsgroups: comp.lang.c++
Subject: Re: C < X < C++, worthwhile(X), solve for X
Keywords: implementation, object oriented, sanity
Message-ID: <752@taumet.com>
Date: 29 May 91 15:45:59 GMT
References: <1991May23.115050.5755@dit.upm.es> <331@nazgul.UUCP>
Organization: Taumetric Corporation, San Diego
Lines: 26

bright@nazgul.UUCP (Walter Bright) writes:

>Not true. Zortech C++ grew out of Zortech C. In fact, the sources for the
>two parsers are the same, with #ifdef's for the differences. It turns out
>that the C++ stuff nearly doubles the size of the parser.

>Myself, (and some others!), thought that implementing a C++ compiler was
>just adding a few keywords, and about 3 months of twiddling. Ha!
>If you want a time estimate, try 2 to 3 years given an existing ANSI C
>compiler.

On the other hand, it took us about 18 months to do our C++ compiler
front end and library entirely from scratch -- we modified an existing
optimizer and code generator from a Pascal compiler.  (This first compiler
was AT&T release 1.2 compatible.  We later spent a few months more to
upgrade to AT&T 2.0 compatiblity.)

This might mean that it is faster to start over than to modify an existing
compiler.  (You can salvage the scanner, preprocessor, and code generator.
Discard the parser and symbol table.)  I know of other development efforts
having spent more than 18 months trying to modify an existing C compiler
without releasing a product.  Some of these efforts were abandoned, others
are still in progress.
-- 

Steve Clamage, TauMetric Corp, steve@taumet.com