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Subject: Re: Tell whether a primitive subprogram was overridden
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Date: 2014-08-18T19:29:48-06:00
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On 18-Aug-14 17:52, Adam Beneschan wrote:
> On Monday, August 18, 2014 4:41:24 PM UTC-7, Victor Porton wrote:
>> Is it possible to determine whether for a given object of type T'Class a
>> primitive subprogram F was overridden (not the same as for type T)?
>>
>> I would like this check for efficiency reasons, not to pass it to a callback
>> if the default "null" operation was not overridden.
>
> No, Ada doesn't provide a mechanism for this.
> I don't know of a language that does, although in some languages you might be
> able to use "reflection" to squeeze the information out, but with some difficulty.
>
> The best solution that I can think of is to add a function to T:
>
>      function F_Does_Something_Useful (Obj : T) return boolean;
>
> This would be False for T, but for any derived type where you override F,
> you'd also override this function to make it return True.
>
>                              -- Adam
>

You *MIGHT* be able to do it w/ LISP; the homoiconic nature and 
first-class functions should combine quite well with the OOP framework 
to allow such a query.