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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Tell whether a primitive subprogram was overridden
Date: Tue, 19 Aug 2014 10:50:21 +0100
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Date: 2014-08-19T10:50:21+01:00
List-Id: <comp.lang.ada>

Victor Porton <porton@narod.ru> writes:

> 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.
>
> No, I won't add this obscure function F_Does_Something_Useful only to
> increase the speed for a tiny bit.

Then you shouldn't be worrying about efficiency in the first place!
(later on, maybe ...)