From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: 'size attribute inheritance
Date: 1997/08/17
Date: 1997-08-17T00:00:00+00:00 [thread overview]
Message-ID: <dewar.871839941@merv> (raw)
In-Reply-To: 33F670EF.4F65@flash.net
Ken said
<<I suppose this is technically true, but couldn't the effect of
pragam Normalize_Scalars, when combined with 'Valid and/or range
checking, be informally described as checking for uninitialized
variables?>>
Be careful! First, Normalize_Scalars does not guarantee that the variable
will be initialized with an out of range value (and indeed for a type
like Integer, it is almost certain that there is no such thing as an
out of range value).
Second, the compiler is in many cases allowed to assume that a variable
is in range, so it may not always do a check where you expect it. In
particular, for a simple assignment, where the subtype is the same on
both sides, there is no requirement to perform a check, since assigning
the out of range value is an acceptable behavior for the error of
referencing an uninitialized variable.
Still, you are generally right, NS will approximate a check for
uninitialized variables in practice.
next prev parent reply other threads:[~1997-08-17 0:00 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-08-09 0:00 'size attribute inheritance Carlos Palenzuela
1997-08-10 0:00 ` Matthew Heaney
1997-08-11 0:00 ` Robert Dewar
1997-08-12 0:00 ` Matthew Heaney
1997-08-13 0:00 ` Ken Garlington
1997-08-13 0:00 ` Matthew Heaney
1997-08-13 0:00 ` Robert A Duff
1997-08-13 0:00 ` Matthew Heaney
1997-08-14 0:00 ` Robert A Duff
1997-08-14 0:00 ` Dale Stanbrough
1997-08-16 0:00 ` Robert Dewar
1997-08-16 0:00 ` Ken Garlington
1997-08-17 0:00 ` Robert A Duff
1997-08-17 0:00 ` Robert Dewar [this message]
1997-08-18 0:00 ` Robert A Duff
[not found] ` <dewar.872433846@merv>
1997-09-03 0:00 ` Robert A Duff
1997-09-06 0:00 ` Robert Dewar
1997-09-08 0:00 ` Robert A Duff
1997-08-10 0:00 ` Robert A Duff
1997-08-10 0:00 ` Robert Dewar
1997-08-11 0:00 ` Matthew Heaney
1997-08-11 0:00 ` Ken Garlington
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