thoughts on "holey" enumerated types

[cs.utexas.edu!utnut!utcsri!csri.toronto.edu!blaak@uunet.uu.net (Raymond]

The thread on converting integers to a sparse enumerated type has got
me thinking.

Couldn't enumerated types always be implemented as a contiguous range, such
that use clauses to specify member ``positions'' just affected the 'POS and
'VAL functions?

That way enumerated type operations (especially loop traversal over a range,
or array indexing) can always be efficient. The only time one needs to know a
member's position is when converting to an integer. Using 'POS and 'VAL seems
safer than unchecked_conversion in these cases anyway.

Ray
blaak@csri.toronto.edu