$ in identifiers -- poll

Steven M. Haflich smh at mit-eddie.UUCP
Sun Dec 9 23:15:10 AEST 1984

Another very ugly but very practical reason for not allowing additional
alphameric characters in identifiers is portability.  Regardless what
the C Standard eventually says, not all machine/OS combinations support
all C-ASCII characters in identifiers (especially externals), and some
support non-C-ASCII characters.  There is little a standards committee
or net.lang.c can do about this [except, I suppose, flame :-)].

My intuition is that languages and OS/linkers most commonly allow
exactly *one* legal nonalphameric character in identifiers, and this
character is most often overloaded as an informal package flag:  `_' as
an external prefix char in Unix/C, `$' in lots of Big Blue systems, etc.
When porting code either direction, the simple one-to-one mapping of
these characters saves a lot of grief.  Let's not make it tougher to
*ex*port Unix/C to other systems by trying to make it very occasionally
easier to *im*port foreign code.

It is my opinion, by the way, that the traditional availability of these
informal package-flag chars inside identifiers was a portability botch,
mostly impeding exporting code, not importing.  But it is only recently
that vendors and their captive language designers have come to realize
that exportability of code can sell machines just as well as

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