Re: Discriminant problem

["Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>]

On 8/29/21 8:51 PM, Simon Wright wrote:
> 
> the compiler says
> 
>     value for discriminant "Node_Test" must be static
>     non-static function call (RM 4.9(6,18))

This has always been the rule for aggregates.

> OK, I get that (tiresome though it is, and I'm amazed I've never come
> across it before), but how to approach it? I seem to be OK with

That is surprising.

>        case Get_Node_Type_Test (T.Node_Type_Part.all) is
>           when Text_Node_Test =>
>              Location_Step.Node_Test :=
>                (Node_Test => Text_Node_Test,
>                 Name      => Null_Unbounded_String);
>           when ...
>        end case;
> 
> but this seems very ugly.

Agreed. What I usually do is

declare
    Result : Whatever (D => Non_Static_Value);
    -- Discriminant of an object need not be static
begin
    Result.F1 := ...;
    ...
    Location_Step.Node_Test := Result;
end;

-- 
Jeff Carter
"You can never forget too much about C++."
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