J3/06-314

To: J3
From: Dan Nagle
Subject: "get kinds" feature
Date: 2006 Oct 24

Dependencies: None

At 177, a straw vote requested a "get kinds" feature
allowing the easy retrieval of all type kind values
in support of the macros feature.

This paper proposes a straw vote to do so.

Here is the straw vote:

For logical kind values,

1.  Add a selected_log_kind() intrinsic

2.  Add a logical_kinds array to iso_fortran_env

3.  Require a logical for each and every integer kind

4.  Undecided

Discussion

Option 1 parallels the real, int and char alternatives,
however, it's not clear how parallel the arguments
would be since there's no range or precision property,
or character set name as in the other cases.

Option 2 allows the number of kinds to be available
as the size of the (presumably) rank-1 array.  Otherwise,
it's a novel approach.  To support macros, perhaps
we want an array for each type.

Option 3 parallels the real and complex relationship.
However, not all vendors currently support a logical
for each integer and vice versa.

A vote in favor of option 1 requires the most work,
option 2 has appeared in earlier paper (04-346r2) so there's
a first draft whence to proceed.  The language
for option three can be made quickly by cribbing
from the existing language for complex.

At any rate, I would like some direction before proceeding.
Hopefully, we can vote this early during 178 to give
plenty of time for several drafts.