RMS comments to X3J11

[karl at haddock.UUCP]

In article <1258 at ho95e.UUCP> wcs at ho95e.UUCP (Bill Stewart) writes:
>Doug's suggestion was to have such constants start with _sys_ and _mach_,
>e.g. _sys_43bsd or _mach_vax.  As an alternative, why not let
>_sys_ and _machine_ be preprocessor variables, leading to
>	#define	_sys_	SysVR2
>	#define	_machine_	u3b2
>and
>	#if _machine_ = vax
[I presume that was a typo for "==".  --kwzh]

Your suggestion is incomplete.  In cpp as currently implemented, your "#if"
would expand into "#if u3b2 == vax" which would be true (!) since tokens with
no definitions are evaluated as zero.

Perhaps you're assuming a hook in cpp to recognize such a comparison and use
the token names instead of their values.  (Perhaps you even intended "=", as
opposed to "==", to distinguish this operation?  I hope not.)  I think such a
rule is too confusing.

Someone else already suggested a variant that I think is more viable:
	#define	_machine_	"u3b2"
could be tested by some comparison operator.  Either "==" or "strcmp(,)==0"
could be used, but since the interpretation is not identical to that of C, I
will suggest a new preprocessor operator "#==".

Karl W. Z. Heuer (ima!haddock!karl or karl at haddock.isc.com), The Walking Lint