🚀 go-pugleaf

In article <1992Nov11.102409.12183@jyu.fi> sakkinen@jyu.fi (Markku Sakkinen) writes:
>In article <5897@balrog.ctron.com> smith@ctron.com writes:
>>In article <9211091022.A01745@MAIL.CASI.NASA.GOV>, thutt@MAIL.CASI.NASA.GOV (thutt) writes:
>>> ...
>>I wouldn't classify enumerations as "superfluous", their removal is a real
>>loss.  But I think the real reason they went was because they are so difficult
>>to type-extend.  Type-extension is Oberon's "thing", and it would be most
>>difficult to set up a mechanism wereby various enumerations were derived from
>>previously-defined enumerations, where certain identifiers are valid for all,
>>but not all identifiers are.
>
>That has obviously been the main reason for eliminating enumerations.
>And even this rationale is very weak.  Only record types can be extended
>in Oberon, not atomic types nor arrays.
>
Enumerations are often used as the discriminent in variant records.  In Oberon
you declare different records that are extensions of a common record.  You also
delcare a different pointer type to each one and the type name of the pointer
takes the place of the enumeration so you get the effect of enumerations, but
it's extendable over module boundries.  Pretty neat!

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| Larry Maturo                      | Opinions expressed herein must be      |
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