Re: Announce: The Ultimate SI Units Cracker

["Randy Brukardt" <randy@rrsoftware.com>]

Wes Groleau wrote in message <3D820229.E1B1BEC8@despammed.com>...
>> It was considered for Ada 9x, but was rejected as having insufficient
>> value for the substantial changes that would be required for
compilers.
>> Most existing Ada compilers do not put attributes in the symboltable;
>> they do not have visibility, and so on.
>
>But they do for 'Write & 'Read, so why not for others?

Not really. 'Read and 'Write don't have visibility at all (they have to
be redefined before freezing). And, in Janus/Ada, they're not actually
in the symbol table -- they are part of the type. (We don't keep type
information in the symbol table at all, just the names of the types).
Types (in Janus/Ada) don't have visibility; they always exist. And,
finally, these items have hard coded definitions in the types; there is
no mechanism for adding others (particularly user defined ones). Other
compilers may differ of course, but user-defined attributes would take
several months of work to implement in Janus/Ada -- and no one had a
compelling enough example to justify making implementors do that sort of
work.

                    Randy.