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From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c
Subject: Re: Variable naming issue
Date: Tue, 25 Apr 2017 11:52:58 -0700
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Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
> bartc <bc@freeuk.com> writes:
>> On 25/04/2017 13:59, Ben Bacarisse wrote:
> <snip>
>>> Whatever their "excuse" it's not code size since tcc /does/ use $, it's
>>> [just] they decided to use it differently.
>>
>> In what way? I've seen it in the source code, but for something called
>> an 'ldname'.
>
> I don't know, but it is pre-processed as a single-character token so
> using it in names would require a change rather than an addition.

The $ character isn't part of the basic source or execution
character set, so it needn't be pre-processed at all.  A conforming
C implementation could easily exist on a system that doesn't support
the $ character at all.  Both ASCII and EBCDIC include it, so that's
not likely in practice -- but in the past there might have been
ASCII-based character sets that substitute some other character
for $ (I'm not sufficiently interested to verify that).

Sure, it might be a one-line compiler change to permit $ in
identifiers.  Actually more than that since it would need to
be diagnosed in conforming mode, unless you want to change the
language to allow it unconditionally -- and even then real-world C
compilers are going to have modes to enforce conformance to earlier
C standards.  And if C identifiers are mapped directly to assembly
language identifiers and/or linker symbols, there will have to be
additional code to generate valid identifiers if the assembler or
linker doesn't like $, or doesn't like it exactly the same way the
C compiler does (can it start an identifier?).

A similar level of work could allow @ and ` in identifiers.  But then
allowing ` would interfere with Markdown, which is commonly used
to quote snippets of C source code, and @ might cause other problems.

Even ignoring all that, the amount of work required to implement
a feature is only one of a number of considerations that should
affect the decision of whether to support that feature.

I've never thought that C's problem is that it doesn't use enough
punctuation characters.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"