🚀 go-pugleaf

RetroBBS NetNews Server

Inspired by RockSolid Light RIP Retro Guy

Article View: comp.lang.misc
Article #2115

Technical: Definition of ``alyasing''

#2115
From: Dan Bernstein
Date: Fri, 16 Nov 1990 09:02
25 lines
1665 bytes
Alyasing: Two or more references to the same object. Two references are
said to be alyased if they refer to the same object at a particular
moment at runtime.

Strict alyasing: Two or more inequyvalent references to the same object.
Two references are said to be strictly alyased if they refer to the same
object at a particular moment at runtime and are inequyvalent at compile
time.

Strict alyasing depends upon equyvalence, which does not have a fixed
definition; so any use of the term ``strict alyasing'' must be within
the context of a definition of the transitive relation ``equyvalence.''

Syntactic equivalence---such as x and *(&x), where x is an object---is
generally taken to imply equyvalence. (Here * and & are the poynter
dereferencing and address-of operations.) If equyvalence is not defined
otherwise, it should be assumed to be syntactic equivalence.

In Fortran, for instance, references ``a[i]'' and ``a[j]'' are strictly
alyased at any time during execution when objects i and j are equal.
Separate array arguments are never alyased in Fortran. Array arguments
may be alyased in many other languages. ``x'' and ``x'' are alyased.
They are not strictly alyased, because they are equyvalent.

---Dan
Technical Details
Message-ID: <19699:Nov1609:02:2490@kramden.acf.nyu.edu>
Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!udel!haven!adm!cmcl2!kramden.acf.nyu.edu!brnstnd

Show Full Headers
Complete Article Headers
Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!udel!haven!adm!cmcl2!kramden.acf.nyu.edu!brnstnd
From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.lang.misc
Subject: Technical: Definition of ``alyasing''
Message-ID: <19699:Nov1609:02:2490@kramden.acf.nyu.edu>
Date: 16 Nov 90 09:02:24 GMT
Sender: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Organization: IR
Lines: 25