Re: Tell whether a primitive subprogram was overridden

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Tue, 19 Aug 2014 16:45:54 +0300, Victor Porton wrote:

> Dmitry A. Kazakov wrote:

>> 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.

You certainly register it only once. Therefore it is indeed the overhead of
a single dispatching call = a couple of nanoseconds. If you are in this
area you should look at C code as well. It checks if something is
registered. The depending on the choice it does a jump or no jump. Jump is
also a nanosecond of so.

Morale: premature optimization is the root of all evil.

[ And you never know if what you are doing would make the code faster,
until you measure it. ]

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de