Re: constructor in abstract tagged types

[Daniel <danielnorberto@gmail.com>]

El miércoles, 8 de mayo de 2019, 21:26:10 (UTC+2), Dmitry A. Kazakov  escribió:
> On 2019-05-08 20:37, Daniel wrote:
> 
> > Hello, im trying to know how can i use abstract tagged types and constructors at the same time.
> 
> Ada does not have proper constructors. But there are various software 
> patterns to work this around.
> 
> > I have this
> > 
> > package FATHERS is
> >    type Father is abstract tagged record
> >       Years : Natural;
> >       field1 : Natural;
> > --    .....and 15 more fields
> >    end record;
> > 
> >    function F_build(Years :Natural) return Father is abstract;
> >    procedure F_forced_to_do_it is abstract;
> 
> private
>     --
>     -- Class-wide initialization of Father's fields
>     --
>     procedure Initialize (Object : in out Father'Class; Years : Natural);
> 
> > end FATHERS;
> > 
> > package FATHERS.SONS is
> > type Son is new father with record
> >     skate : boolean;
> > end Son;
> > 
> > function F_Build(Years :Natural) return Son;
> > procedure F_Forced_to_do_it;
> > end FATHERS.SONS;
> > 
> > package body FATHERS.SONS is
> > 
> > function F_Build(Years : Natural) return Son is
> > begin
>       return Result : Son do
>          Initialize (Result, Years); -- Parent's "constructor"
>          Result.Skate := True;
>       end return;
> > end F_Build;
> > 
> > end FATHERS.SONS;
> 
> -- 
> Regards,
> Dmitry A. Kazakov
> http://www.dmitry-kazakov.de

Thank you Dmitry. It really works for me!