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From: Victor Porton <porton@narod.ru>
Newsgroups: comp.lang.ada
Subject: Re: Tell whether a primitive subprogram was overridden
Date: Tue, 19 Aug 2014 16:45:54 +0300
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Date: 2014-08-19T16:45:54+03:00
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Dmitry A. Kazakov wrote:
> On Tue, 19 Aug 2014 02:41:24 +0300, 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)?
> 
> It is always overridden even if inherited. Purely formally, since the type
> is different, e.g. S derived from T, then it cannot be the same
> subprogram.
> [Technically it can have some additional trampoline code as well.]
> 
>> I would like this check for efficiency reasons, not to pass it to a
>> callback if the default "null" operation was not overridden.
> 
> You mean that a check would be more efficient than a dispatching call? I
> don't think there would be much difference, except the case when the
> subprogram has a long list of additional arguments or computed arguments.
> That is usually the case when doing tracing stuff. In that case you could
> think of some lazy parameter evaluation schema or upfront checks as Adam
> suggested.

No. I haven't described exactly what I do.

I need to register (by calling a C function) a C wrapper around a method of 
my class as a callback subprogram. If my method is null, it is not necessary 
to register it and the C code would not call it.

-- 
Victor Porton - http://portonvictor.org