4 Jan
2017
4 Jan
'17
3:35 a.m.
On Tue, Jan 3, 2017 at 3:19 PM, Doug McIlroy <doug(a)cs.dartmouth.edu> wrote:
Curmudgeonly comment: I bristle at the coupling of
"ifdef" and "portable".
Ifdefs that adjust code for different systems are prima facie
evidence of NON-portability. I'll buy "configurable" as a descriptor
for such ifdef'ed code, but not "portable".
I hear you and partially agree. But I would point out that my experience
in 40+ years of professional "coding" the programs that have "lasted"
the
longest and matured the most over time, were all written in a language that
had some sort of preprocessor. Using a preprocessor is not a bad thing,
it's the miss use that is the problem and leaving it out I think weakens
the language.
IIRC: Brian made this same point in the "Why Pascal is not my Favorite
Programming Language."
I think your point of over use, is valid (like symlinks in the file system
- my curmudgeonly beef) - just because we >>have<< a feature does not make
it the best way to do something. I like to think of this sort of choice
as "good taste" -- simple and elegant. ifdef's are a real solution to
a
problem. But like you, I >>hate<< seeing them all over the place and they
certainly can muck up the code.
BTW: I much prefer a local_func.c which sucks in unix_bindings.c,
vms_bindings.c, winders_bindings.c or the like with ifdefs and alls the
configuration control needed in >>one<< place; and then all of the rest of
the code try to be a pure as possible as you describe.
FWIW: One of the best I ever saw was the old FORTRAN SPICE 2G6 of Ellis
Cohen and Tom Quarles. That program runs everywhere (still does). Ellis
and Tom used m4 to preprocess it, IIRC and keeps the localization in a very
controlled space. If you even looked at it, Ellis does some really
imaginative coding (compiling the internal loop in a data block and jump to
it), it all portable and actually very easy to understand. For one thing
the comments are there and very, clear.
But Ellis has great style and have mopped up after a number of other of the
UCB greats in those days, I'd much rather deal with Ellis's and TQ's code
base then some of my other peeps.
Anyway - I agree - ifdef >>is<< miss used in way too much code, but I think
part of that is so many programmers never had a real software engineering
course ( a thought I will follow up in another thread).
Clem