Re: Trouble with "operation can be dispatching in only one type"

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 14-08-13 22:23 , Victor Porton wrote:
> I defined two tagged types T1 and T2 in some package.
> 
> I need a function in the same package:
> 
> not overriding function F (Stack: T1) return T2;
> 
> The compiler complaints:
> 
> operation can be dispatching in only one type
> 
> My current workaround is to define it instead as:
> 
> not overriding function F (Stack: T1'Class) return T2;
> 
> But this is a hack. Can I define this function in the right way? (I want it 
> to be dispatching only in T1, not T2.)

To be dispatching in T1, but not in T2, it should be

   function F (Stack : T1) return T2'Class;

If the use of 'Class to prevent dispatching is a problem for you,
another way is to put the two type declarations in different packages.

A function F can be dispatching only in the type declared in the same
package as F. For example, if T2 is declared in a different package than
T1 (including a package nested within the package that declares T1) then
you can declare function F (Stack : T1) return Some_Pkg.T2 and it will
dispatch only in T1 (assuming that T1 and F are declared in the same
package declaration).

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
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