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From: adam@irvine.com (Adam Beneschan)
Subject: Re: Syntax question
Keywords: help syntax
References: <3jrt1m$9rk@erinews.ericsson.se>
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Date: Thu, 16 Mar 1995 19:20:50 GMT
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Date: 1995-03-16T19:20:50+00:00
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etlghh@garbo.ericsson.se (Geoffrey Hollingworth) writes:
>Hi
>
>I am currently researching into real time languages and hope
>you ada experts can explain something to me.  I apologise for
>my lack of knowledge in ada.
>When binding formal parameters with actual parameters the '=>'
>operator is used, irrespective of whether the formal parameter
>is declared as IN, INOUT or OUT.  Is there a reason for this ?
>If I proposed an alternative syntax where "=>" indicated the FP
>was an IN parameter, "<=" to indicate an OUT parameter and "<=>"
>to indicate an INOUT.
>Then the caller of the procedure/function would have explicitly
>had to understand to direction of the parameters and at the same
>time increased the readability of his/her code.
>Is there a fundamental flaw in this line of thinking ?
>Does ada manage this problem via a different mechanism ?

The main flaw with your proposal is that <= already has a meaning
(less than or equal).  Other than that, though, I think it would have
been a good idea.

I seem to remember that an early definition of Ada, while the language
definition was still in the works, used := for IN parameters, =: for
OUT (or was it vice versa?), and :=: for IN OUT.  Does anyone else
remember this, or know why the idea was scrapped?

                                -- Adam