Re: Access to function causes "access check failed"

Re: Access to function causes "access check failed"

[Robert A Duff]

Alex <alexandre.konieczny@gmail.com> writes:

> The My_T : T1 declaration in t.adb caused the check failed error on
> line of "type T1 is record". I wonder why I have such an error, if
> it's normal or not. Any ideas ?

Access values are default-initialized to null, and you declared the
thing "not null", so it raises C_E when initialized.

Try a subtype predicate (Ada 2012 feature); they're better behaved in
this regard.

- Bob

Re: Access to function causes "access check failed"

[Niklas Holsti]

On 11-12-27 23:20 , Alex wrote:
> Hi everyone!
>
> I have a question about access to functions. With the example below :
>
> --  main.adb
> with T;
> procedure Main is
> begin
>     T.P;
> end Main;
>
> --  t.ads
> package T is
>     type T_Procedure_Params_Access is not null access
>       function (Request : Integer;
>                 Params  : Integer) return Integer;
>
>     procedure P;
> private
>     type T1 is record
>        I : T_Procedure_Params_Access;
>     end record;
> end T;
>
> --  t.adb
> package body T is
>     My_T : T1;
>     procedure P is
>     begin
>        null;
>     end P;
> end T;
>
> The My_T : T1 declaration in t.adb caused the check
> failed error on line of "type T1 is record". I wonder why
> I have such an error, if it's normal or not. Any ideas ?

You have declared T_Procedure_Params_Access as "not null", but the 
component T1.I is not given an initial value, so the declaration of My_T 
gives My_T.I the default initial value null, which fails the "not null" 
constraint.

Either remove the "not null" constraint on T_Procedure_Params_Access, or 
give My_T.I a non-null initial value in some way.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
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