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Date: Wed, 11 Jun 2008 17:02:48 +0200
From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
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Newsgroups: comp.lang.ada
Subject: Re: Interface specification in Ada
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Date: 2008-06-11T17:02:48+02:00
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christoph.grein@eurocopter.com schrieb:
> You missed the "this" parameter, which is implicit in Java, but
> explicit in Ada:
> 
> package Bicycle is
>   type Object is interface;
> 
>   procedure changeCadence (Ob: in out Object; newValue : in Integer)
> is abstract;

And in Ada 2005 the "this" parameter can be suitably
named, and when used, it can be written just like in
Java,

   Peugeot: Bicyle.Object;

   Peugeot.changeCadence(27);

Incidentally, I'd suggest you consider defining distict integer
types that reflect gears etc. By doing so you can have the
compiler check that a cadence number is not inadvertently
used as a gear number. E.g.,

   type Gear is range 1 .. 21;
...
   procedure changeGear
      (The_Bike: in out Object; newValue : in Gear) is abstract;

or

   type Gear
     (Front_Wheel: Wheel_Number;
      Rear_Wheel: Wheel_Number)
   is private;

and so on.