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From: guest@stat.fsu.edu (a guest account)
Newsgroups: comp.lang.fortran
Subject: Pointers to array sections
Keywords: pointers, alias, identify, orthogonality
Message-ID: <750@stat.fsu.edu>
Date: 17 Jun 89 17:34:02 GMT
Reply-To: mccalpin@scri1.scri.fsu.edu
Distribution: usa
Organization: Supercomputer Computations Research Institute
Lines: 19

If the standard really requires that pointers be able to point to
arbitrary array sections, then there is not much need for the (deleted)
SET RANGE feature.  Since SET RANGE would presumably be used when you
want to access a particular array section repeatedly, setting up
pointers to the appropriate sections in the RANGE group would not be
difficult. Not smart, perhaps, but not difficult....  It is easy to
imagine that a compiler could do a much better job optimizing a static
ALIAS than a run-time POINTER for this task.

The ALIAS, IDENTIFY, POINTER, and SET RANGE options all overlap
somewhat. (Quiz: which of the above are in the current draft
standard?).  It is not clear that the most general mechanism (the
extended pointers?) is the most reasonable or efficient.  I think
Algol-68 is a good example to how a very orthogonal language is not
necessarily the most comprehensible.  Using the same pointer paradigm
for array section aliasing and recursive data structures seems more
likely to confuse than clarify the code.
--
John D. McCalpin	mccalpin@masig1.ocean.fsu.edu