Dollars and Sense

[george at idis.UUCP]

References: gitpyr.422

There has been much discussion lately about using dollar signs
in identifier names or providing a mechanism in a C program
to associate a particular linker or assembler symbol with a particular
identifier.

It is clear in both C (K&R 1978) and ANSI C (draft 84-131)
that a legal C program does not have dollar signs in identifiers.
(Section 10.4 of appendix A with the ANSI draft discusses this,
but it is explicitly stated that this is not part of the standard.)

Since a program which has dollar signs in tokens is distinct
from any legal program, a compiler is free to do anything with
it including treating those tokens as identifiers.

Robert Viduya in article gitpyr.422 says:

> Perhaps what C really needs is a way to define a seperate external name for
> an identifier when declaring that identifier.  For example, the following:
> 
>     extern sys_read "SYS$READ" ();
> 
> would tell the compiler/linker to call the entrypoint  "SYS$READ"  whenever
> "sys_read"  was called in the source.

I do not think that C source is the appropriate place to put
this information, but if one must, why not use the normal mechanism.

	asm("_sys_read = SYS$READ") ;

On many UNIX brand systems, subroutines that call system calls
are written in assembly language and the object code is put in a library.
The subroutines provide both the appropriate subroutine linkage and return
sequence for C programs and the appropriate naming convention for C programs.
This seems to me to be a reasonable solution that could be used
in other applications or systems if it is necessary to deal
with strange symbols.
This is probably preferable to all of the preceding methods of dealing
with such symbols.


	George Rosenberg
	idis!george