From: Robert A Duff <bobduff@world.std.com>
Subject: Re: disjoint ranges ?
Date: 2000/10/17
Date: 2000-10-17T00:00:00+00:00 [thread overview]
Message-ID: <wccr95fobf6.fsf@world.std.com> (raw)
In-Reply-To: 39EBB984.F2F8905F@ix.netcom.com
Lao Xiao Hai <laoxhai@ix.netcom.com> writes:
> So, making a feature more powerful might be something such as being
> able to overload the "in" membership test.
It might be in the abstract, but in the context of Ada, probably not.
>... For some reason, this
> operator is not really a first class operator in Ada. I have often
> wondered about the rationale for that decision.
What is the type of the right-hand side of "in" here:
if X in Integer range 1..10 ...
? Ada has no way of describing that type. In order to make "in" a
normal operator, we would need to invent a way to pass types as
parameters, and talk about the type of a type (and subtypes). This is
not entirely unreasonable in the abstract, but it would be an enormous
change to Ada.
Consider:
type T is range 1..100;
function "in"(X: T; Y: type-of-T?) return Boolean;
Or maybe it should be T'in? Anyway, it raises all kinds of questions.
What *is* the range of T (given that "in" changes it)?
- Bob
next prev parent reply other threads:[~2000-10-17 0:00 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-10-12 0:00 disjoint ranges ? Philippe Torres
2000-10-12 0:00 ` Pat Rogers
2000-10-12 0:00 ` Ehud Lamm
2000-10-12 0:00 ` Pat Rogers
2000-10-13 0:00 ` Ehud Lamm
2000-10-13 0:34 ` Jeff Carter
2000-10-13 0:00 ` Philippe Torres
2000-10-14 3:12 ` Robert Dewar
2000-10-16 0:00 ` Robert A Duff
2000-10-16 0:00 ` Lao Xiao Hai
2000-10-17 0:00 ` Robert A Duff [this message]
2000-10-17 0:00 ` Lao Xiao Hai
2000-10-18 0:00 ` dmitry6243
2000-10-18 0:00 ` Robert Dewar
2000-10-18 0:00 ` Robert A Duff
2000-10-19 3:08 ` Overloading "in" (was: disjoint ranges ?) Jeff Carter
2000-10-19 0:00 ` Ehud Lamm
2000-10-21 0:00 ` Robert Dewar
2000-10-21 0:00 ` Jeff Carter
2000-10-16 0:00 ` disjoint ranges ? Robert Dewar
2000-10-13 0:00 ` Marin David Condic
2000-10-14 3:14 ` Robert Dewar
2000-10-13 0:00 ` Philippe Torres
2000-10-13 0:00 ` Lao Xiao Hai
2000-10-14 3:17 ` Robert Dewar
2000-10-16 0:00 ` Robert A Duff
2000-10-13 0:00 ` wayne lydecker
2000-10-13 0:00 ` wayne lydecker
2000-10-13 0:00 ` Lao Xiao Hai
2000-10-23 0:00 ` Charles Hixson
2000-10-24 0:00 ` dmitry6243
2000-10-24 0:00 ` Andrew Cooke
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