Re: Renaming enumeration literals?

[firth@sei.cmu.edu (Robert Firth)]

In article <EACHUS.92Mar20150027@Dr_No.mitre.org> eachus@Dr_No.mitre.org (Rober
t I. Eachus) writes:

>     I'll take your question as serious and not rhetorical.  First of
>all a compiler which rejects a static instance of a renamed function
>as a choice in a case statement is wrong.  (See AI-438/09-BI-WA
>Renamed enumeration literals can be static.)

Just to complete the exposition: yes, it was an oversight in the original
RM that a renamed enumeral wasn't static; as Robert Eachus points out,
this was discovered and corrected.

The reason this renaming rule is used is that both enumerals and functions
may be overloaded; from the point of view of visibility and overload
resolution, an enumeration literal is simply a parameterless function
that always returns the same value.  This semantic unification is a
help to both compiler writer and user, I think.

And the reason enumerals may be overloaded is so that the programmer
can define different character sets with the same literals, thus

	ASCII'('A')
	EBCDIC'('A')

If the application requires a non-ASCII character set, this makes the
program much clearer, since 'A' can always mean "whatever would look
like letter-A on input or output".  The wisdom of this design decision
will become even more evident when we move to ISO Latin-1 as the
standard, and many programs will have to support two character sets
during the changeover.