Just a few more gripes after a hard day porting. Common folks - a little
rigor up front would save a ton of work...
1. Do NOT use any of the following to indicate OSF/1
#ifdef ALPHA
#ifdef alpha
#ifdef __ALPHA
#ifdef __alpha
#ifdef axp
etc.
Right now the AXP chips run OSF/1 & VMS & WNT. A Linux
version is in the works too. So trying to mark OSF/1 by specifying the
chip is a *poor* idea. It's possible that OSF1 might run someday
on another processor too. Solaris runs on multiple platforms, so
does WNT. Additionally, OS's that run on multiple platforms need
a symbol for any platform (shared things, like directory syntax) and
for each platform (for data types which may have different length.)
Something along the following lines would be good:
#ifdef axpOSF /* OSF/1 on AXP */
#ifdef axpWNT /* WNT on AXP */
#ifdef axpVMS /* VMS on AXP */
#ifdef vaxVMS /* VMS on VAX */
#ifdef anyVMS /* VMS on any platform */
#ifdef riscSOLARIS /* Solaris on RISC */
#ifdef intelSOLARIS /* Solaris on Intel */
#ifdef anySOLARIS /* Solaris on any platform */
#ifdef intelLINUX /* Linux on Intel */
#ifdef axpLINUX /* Linux on AXP */
#ifdef anyLINUX /* Linux on any platform */
2. Ok, you can't know ahead of time what platform somebody is going to
port your software to, but just think how much fun it is to
dig through a nested set of ifdefs that look like the following in
order to figure out where to patch in for a new OS:
#if defined(A) || defined(B)
#if !defined(C)
#else
#if OPTION1
#else
#endif
#endif
#else
#if OPTION1
#if defined(D)
#else
#endif
#else
#endif
#endif
I suggest that developers not worry quite so much about saving space
and expand these things so that they are easier to read and understand.
In particular, ditch the unqualified #else's - it's way too easy to
drop through one of these. For instance
/*Stuff common to a couple of platforms*/
#if defined(PlatformA) || defined(PlatformB) || defined(PlatformC)
#endif
/*Stuff specific to each platform - notice, no #else */
#if defined(PlatformA)
#endif
#if defined(PlatformB)
#endif
#if defined(PlatformC)
#endif
3. I'd also like to point out that if more of you would use the ANSI C
switches on your compilers you'd find one heck of a lot fewer
#ifdefs in your code!
Developers, please take a minute to check your makefiles. Is the "ANSI
C compliant" switch set? Do NOT assume that just because you have an
ANSI C compiler that it is running in ANSI C mode - every C compiler
I've seen defaults to a "relaxed" mode, and none of them have the
*same* relaxed mode.
If you are writing in C, but not checking for ANSI C compliance,
please post here your rationale for writing nonstandard, nonportable
code.
Regards,
David Mathog
mathog at seqvax.bio.caltech.edu
Manager, sequence analysis facility, biology division, Caltech
