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Subject: Re: Record initialisation question
Newsgroups: comp.lang.ada
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From: DrPi <314@drpi.fr>
Date: Fri, 15 Jan 2021 08:50:39 +0100
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Le 14/01/2021 à 17:53, Shark8 a écrit :
> Another option, which IIUC should work within the constraints, being Pure:
> 
> With
> Ada.Unchecked_Conversion,
> System;
> 
> Package Example with Pure is
>      
>      Type Address_Stub is null record
>        with Size => Standard'Address_Size, Warnings => Off;
>      Function Convert(Input : System.Address) return Address_Stub;
>      
>      Type Stub is null record with Size => 8, Warnings => Off;
>      Type Static_Record is record
>          Reserved_1 : Stub;
>          X, Y       : Integer;
>          Self       : Address_Stub;
>      end record;
>      
>      Generic
>          Location : System.Address;
>      Package Based is
>          
>          Function Create( X, Y : Integer ) return Static_Record;
>      Private
>          Function Create( X, Y : Integer ) return Static_Record is
>            (Self => Convert( Location ), Reserved_1 => (null record),
>             X => X, Y => Y
>            );
>      End Based;
>      
>      
> Private
>      Use System, Ada;
>      
>      Function Address_Conversion is new Unchecked_Conversion(
>         Source => Address,
>         Target => Address_Stub
>        );
>      Function Convert(Input : System.Address) return Address_Stub
>        renames Address_Conversion;
> End Example;
> 
> -- Usage should be something like:
> Object_Address : Constant System.Address := (<>);
> Package Object_Basis is new Example.Based( Object_Address );
> Object : Example.Static_Record := Object_Basis.Create( Params => <> );
> For Object'Address use Object'Address;
> 
> Sorry but I haven't done much in the way of microcontrolers, so this is best-guess on my part. The restrictions of Pure *should* comport with the restrictions you have though, again IIUC.
> 
Unchecked_Conversion is not compatible with no elaboration code.