From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=ham autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,a81d7835683dac7b X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2003-09-14 17:17:44 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!arclight.uoregon.edu!wn13feed!wn11feed!worldnet.att.net!204.127.198.203!attbi_feed3!attbi_feed4!attbi.com!sccrnsc01.POSTED!not-for-mail Message-ID: <3F650511.1070902@attbi.com> From: "Robert I. Eachus" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.0.2) Gecko/20021120 Netscape/7.01 X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.lang.ada Subject: Re: Bases 1.52 References: <4a4de33a.0309021059.53f71234@posting.google.com> <4060780.x1l89WMggb@linux1.krischik.com> <17eddf9f.0309092349.2ff22de2@posting.google.com> <1301057.xhkpTmYQhd@linux1.krischik.com> <3F64B1B3.2070305@attbi.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit NNTP-Posting-Host: 24.34.139.183 X-Complaints-To: abuse@comcast.net X-Trace: sccrnsc01 1063585064 24.34.139.183 (Mon, 15 Sep 2003 00:17:44 GMT) NNTP-Posting-Date: Mon, 15 Sep 2003 00:17:44 GMT Organization: Comcast Online Date: Mon, 15 Sep 2003 00:17:44 GMT Xref: archiver1.google.com comp.lang.ada:42504 Date: 2003-09-15T00:17:44+00:00 List-Id: Nick Roberts wrote: > "Robert I. Eachus" wrote in message > news:3F64B1B3.2070305@attbi.com... > > >>But like unbounded string types, or a discriminated record >>type without a default value for the discriminant, you must >>provide an initial value > > > An initial value is not required for an object of type > Ada.Strings.Unbounded.Unbounded_String. It is initialised by default to an > empty string [RM95 A.4.5.(73)]. I guess you meant "... like objects declared > as being of an unconstrained subtype with no constraint, such as 'String', > or of a discriminated record subtype which does not have default expressions > for the discriminants and with no constraint, ...". That is why I said unbounded string types--all lower case--not type Unbounded_String. But I did make a mistake, I really meant to write unbounded array types, which is a lot clearer. > Do you mean other than the term "indefinite"? [RM95 3.3(23), 3.7(26)] Yes. But it is really hard to express what I meant. There are types whose subtype is indefinite, where you can either add a constraint when declaring an object, or provide an initial value. But there are also indefinite types where you cannot provide a constraint, and must provide an initial value. These are currently "types with unknown discriminants" all types with unknown discriminants are indefinite, but not all indefinite subtypes are types with unknown discriminants. I think in one ARG discussion we called these types "really indefinite types" and in another discussion "initial value only types" but neither of those names is much shorter than "types with unknown discriminants." (Notice that classwide types are not really types with unknown discriminants, but 3.3(29) defines them to be.) This may seem to be much ado about nothing, but these types are those that cannot be subcomponents, so it is a pretty important group. -- "As far as I'm concerned, war always means failure." -- Jacques Chirac, President of France "As far as France is concerned, you're right." -- Rush Limbaugh