From: mfeldman@seas.gwu.edu (Michael Feldman)
Subject: Re: Pre-condition vs. Post-condition
Date: 26 Mar 91 23:36:40 GMT [thread overview]
Message-ID: <2937@sparko.gwu.edu> (raw)
In-Reply-To: 5074@goanna.cs.rmit.oz.au
O'Keefe's posting gave such a good discussion of the issues that there's not
much to add, except the following:
The whole thread started with preconditions. I think Ada has a chance to
make life a whole lot easier by making it _possible_ to initialize all
types with default initial values, consistently. I am not interested in
having clients depend upon the initial values; rather I want clients
to be able to depend on variables, types, whatever, _not_ being
_uninitialized._ There will always be something in there that's
"in-range" for the type. Clearly Ada83 thought this was worth doing for
access types, and look how much easier it is to write linked-list
packages because there are no garbage pointers to worry about (leave
aside the dangling-pointer problem left unsolved by Unchecked_Deallocation!)
I was told once by an Ada83 high priest that the reason record fields can
be initialized is that, syntactically, it's "free" because the syntax
of a field declaration is the same as the syntax of a variable declaration.
I got the impression that the thinking didn't go much deeper than that.
They didn't bother with initializers for other types because it wasn't free.
Mike
next prev parent reply other threads:[~1991-03-26 23:36 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
1991-03-24 21:23 Pre-condition vs. Post-condition stt
1991-03-25 16:00 ` Arthur Evans
1991-03-25 17:05 ` Michael Feldman
1991-03-26 4:31 ` Jim Showalter
1991-03-26 10:21 ` Richard A. O'Keefe
1991-03-26 16:44 ` Michael Feldman
1991-03-26 22:03 ` Richard A. O'Keefe
1991-03-26 23:36 ` Michael Feldman [this message]
1991-03-28 20:43 ` Pre-condition vs. Post-condition (actually inintialization) Dana Carson
1991-03-27 21:34 ` Pre-condition vs. Post-condition Jim Showalter
1991-03-28 2:54 ` Michael Feldman
1991-03-29 3:28 ` Jim Showalter
1991-03-27 3:12 ` Jim Showalter
1991-03-27 21:32 ` Initialization Paul Stachour
-- strict thread matches above, loose matches on Subject: below --
1991-03-18 15:47 Pre-condition vs. Post-condition "Norman H. Cohen"
1991-03-15 3:57 Chris M. Little
1991-03-15 19:07 ` Michael Feldman
1991-03-17 12:26 ` George C. Harrison, Norfolk State University
1991-03-18 15:04 ` Joe Hollingsworth
1991-03-18 19:51 ` Marlene M. Eckert
1991-03-19 19:07 ` Michael Feldman
1991-03-21 3:01 ` Jim Showalter
1991-03-21 18:40 ` Michael Feldman
1991-03-19 20:38 ` Charles H. Sampson
1991-03-21 3:06 ` Jim Showalter
1991-03-19 21:07 ` Jim Showalter
1991-03-19 7:38 ` Jim Showalter
1991-03-19 14:46 ` Joe Hollingsworth
1991-03-21 2:46 ` Jim Showalter
1991-03-22 15:18 ` Brad Balfour
1991-03-19 18:17 ` Mike Gilbert
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