C standardization (linkers, #if, enums)

[mrm at datagen.UUCP]

Regarding several of the news items:

    1)	Six character mono-case linkers.  These are a fact of life on many
	non-UNIX systems.  In fact on RDOS (a Data General real-time OS),
	the object module originally only allowed 5 characters, monocase,
	since by using RAD50, 1 identifier would fit in 2 16-bit words.
	Also, ADA will not necessarily spur OS-vendors into having linkers
	that accept both cases without translation, since ADA is defined
	as a mono-case language.  Also, living with other languages (and
	their object formats) is also a reality, that cannot be ignored.
	I know people that routinely link C, FORTRAN, PL/1, and assembler
	together.  Finally, changing object formats is a b*tch, since
	outside of UNIX, compilers produce object code directly (ie, every
	compiler, linker, library editor, etc.) must be changed.  I know,
	we've been looking at changing object module formats at DG.

    2)	#if expressions:  The new ANSI standard will add the use of
	defined(name) in #if and #elif's.  Also, #elif was added for else if.
	While #ifdef and #ifndef are still allowed, #if defined(name) and
	#if !defined(name) have more power, ie, you can use && and || on
	them, so you could say:

		#if	defined(VMS) || defined(OS360)
		    ....
		#elif	defined(UNIX)
		    ....
		#else
		    ....
		#endif

	I don't remember whether __LINE__ and __FILE__ made it in, but I
	seem to remember that they did.

    3)	What to do about enum's still divides the committe.  Some favour
	eliminating them (in favour of either #define or the new const
	sub-type), others want to treat them as integer constants, and
	still others want strict type-checking on them.
	
	My own view is that there exists a need for them, and neither
	alternative meets that need (you run out of stack space on many
	compilers if you have more than 150 defines that are defined in
	terms of the previous define, and const's in a typically implement-
	ation would be initialized readonly variables, and hence could not
	be used in case statements).  Since #define's are typically not
	known to the compiler, enum's (and const's) at least have a chance
	of being exported to a symbolic debugger.

	Michael Meissner
	Data General Corporation
	...{ ihpn4, rocky2, decvax!ittvax, allegra }!datagen!mrm