From: "Jean-Pierre Rosen" <rosen@adalog.fr>
Subject: Re: 'Valid, subtypes and constraint checking
Date: Fri, 26 Sep 2003 15:13:42 +0200
Date: 2003-09-26T15:13:42+02:00 [thread overview]
Message-ID: <52e1lb.bua.ln@skymaster> (raw)
In-Reply-To: bl18e1$6ot2h$1@ID-69815.news.uni-berlin.de
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"Peter Amey" <peter.amey@praxis-cs.co.uk> a �crit dans le message de news:bl18e1$6ot2h$1@ID-69815.news.uni-berlin.de...
> Some guidance please to reduce the slight panic I am suffering from.
>
> When reading in values from an external device it is important to check
> that the value read is a valid representation for its type. The read
> values are also considered volatile so each read returns a potentially
> different value.
> [...]
> (Horrible strawman solution: do an unchecked conversion of External_Port
> into Temp and then do the validity check).
>
Not a horrible solution. You cannot assume your value is a T until you have checked
for it!
As long as all you know is that it is a set of bits, put it in a variable appropriate for
sets of bits. *After* validity checking, you can consider it a T. And Unchecked_Conversion
is the appropriate tool for changing the view on a give set of bits.
--
---------------------------------------------------------
J-P. Rosen (rosen@adalog.fr)
Visit Adalog's web site at http://www.adalog.fr
next prev parent reply other threads:[~2003-09-26 13:13 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-26 11:41 'Valid, subtypes and constraint checking Peter Amey
2003-09-26 13:13 ` Jean-Pierre Rosen [this message]
2003-09-26 18:18 ` Jeffrey Carter
2003-09-26 21:48 ` Chad R. Meiners
2003-09-27 1:30 ` Robert I. Eachus
2003-09-29 7:27 ` 'Valid, subtypes and constraint checking - Thanks Peter Amey
2003-09-30 2:58 ` Robert I. Eachus
2003-09-30 12:45 ` Marin David Condic
2003-09-30 21:30 ` Robert I. Eachus
2003-10-01 12:44 ` Marin David Condic
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