Re: Syntax question

[mfeldman@seas.gwu.edu (Michael Feldman)]

In article <3jrt1m$9rk@erinews.ericsson.se>,
Geoffrey Hollingworth <etlghh@garbo.ericsson.se> wrote:

>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.

This is an interesting idea, but of course it's not part of the language.
The => is used as a general sort of binding operator:

- formal to actual parameters
- formal to actual discriminants (variant record tags)
- in CASE and exception handler clauses

etc.

In the first two cases, it is quite legal to omit the named association,
that is, a procedure P(X: T1; Y OUT T2; Z :IN OUT T3) can be called
using positional asociation: P(A,B,C).

The named association is very convenient in teaching about parameters,
and makes for nice readable code (IMHO, of course), but in general is
really "syntactic sugar." 

Mike Feldman
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Michael B. Feldman -  chair, SIGAda Education Working Group
Professor, Dept. of Electrical Engineering and Computer Science
The George Washington University -  Washington, DC 20052 USA
202-994-5919 (voice) - 202-994-0227 (fax) - mfeldman@seas.gwu.edu (Internet)
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