From: elroy.jpl.nasa.gov!swrinde!mips!samsung!caen!umeecs!dip.eecs.umich.edu!wa rack@ames.arc.nasa.gov (Christopher Warack)
Subject: Re: 'SIZE attribute of a type
Date: 12 Dec 91 15:18:20 GMT [thread overview]
Message-ID: <1991Dec12.151820.25797@zip.eecs.umich.edu> (raw)
In article <5898@email.sp.unisys.com> parkhill@email.sp.unisys.com (parkhill) w
rites:
>>parkhill@email.sp.unisys.com (parkhill) writes:
>>>Image a compiler was smart enough to understand baised number ranges.
>>
>>> type b is range 9 .. 10;
>>> or
>>> type b is range 2**31 - 2 .. 2**31 - 1;
>>
>>
>>>If the compiler can generate code that only uses 1 bit then b'Size
>>>should return 1.
>>
>>Oh, that compilers were so cleverly written!
>>
>
>> Deleted text.
>
>My point on the compiler having the capability to use one bit is that I
>find the utility of type_name'size is now questionable. Lets say the
>compiler is capable of using 1 bit but won't do it in most situations.
>How can any programmer use type_name'size to any practical purpose? It
>seems less useful than Entry_Name'Count. However, I am sure that the
>justification for the change to type_name'size is rock solid.
Seems to me that the only reason you'd want the minimum number of bits
used to represent a type is if you wanted to implement that type with the
minimum number of bits allowed, eg, in a maximally packed record using
a "somewhat" portable rep clause. (Not the most beautiful piece of code I
can imagine).
If you wanted to know the number of bits in a certain type of object (e.g,
a variable of a type) use object'size -- that's what it's for.
-- Chris
--
Christopher A. Warack warack@eecs.umich.edu
Graduate Dept, EECS (313) 665-4789
University of Michigan
next reply other threads:[~1991-12-12 15:18 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
1991-12-12 15:18 elroy.jpl.nasa.gov!swrinde!mips!samsung!caen!umeecs!dip.eecs.umich.edu!wa [this message]
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1991-12-13 17:24 'SIZE attribute of a type elroy.jpl.nasa.gov!swrinde!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!ds
1991-12-13 16:00 Alex Blakemore
1991-12-13 15:23 agate!spool.mu.edu!yale.edu!qt.cs.utexas.edu!zaphod.mps.ohio-state.edu!ca
1991-12-12 22:49 Robert I. Eachus
1991-12-12 15:36 elroy.jpl.nasa.gov!sdd.hp.com!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu
1991-12-12 3:17 Mark Biggar
1991-12-11 18:29 elroy.jpl.nasa.gov!swrinde!zaphod.mps.ohio-state.edu!unix.cis.pitt.edu!gv
1991-12-10 12:30 mcsun!uknet!yorkohm!minster!mjl-b
1991-12-10 8:23 paul goffin
1991-12-09 13:24 Ed Matthews
1991-12-07 0:32 Donald Gardner
1991-12-06 21:14 Ed Matthews
1991-12-06 21:07 Richard Pattis
1991-12-06 20:15 parkhill
1991-12-06 20:04 parkhill
1991-12-06 18:50 Brian Hanafee
1991-11-14 20:15 cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!pacbell.com!iggy.GW.Vit
1991-11-14 19:58 cis.ohio-state.edu!zaphod.mps.ohio-state.edu!mips!pacbell.com!iggy.GW.Vit
1991-11-14 16:45 Danford Lehman
1991-11-13 17:01 elroy.jpl.nasa.gov!sdd.hp.com!mips!zaphod.mps.ohio-state.edu!unix.cis.pit
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