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From: Ludovic Brenta <ludovic@ludovic-brenta.org>
Newsgroups: comp.lang.ada
Subject: Re: speed of generic code in Ada (vs Java)
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Date: Sat, 17 May 2008 10:07:48 +0200
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Date: 2008-05-17T10:07:48+02:00
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jhc0033@gmail.com writes:
> Ludovic Brenta wrote:
>> jimmaureenrogers writes:
>> > On May 16, 11:31 am, "jhc0...@gmail.com" <jhc0...@gmail.com> wrote:
>> >> Java only allows 'objects' as generics parameters. So, if you define a
>> >> generic class and use 'Integer' as a parameter, your code will be slow
>> >> because of the boxing - up to 5x compared to non-generic Int (see the
>> >> recent discussion in comp.lang.java.programmer - the 'numerics'
>> >> thread). Is the situation similar with generics in Ada, GNAT,
>> >> specifically?
>>
>> > No.
>>
>> To add to Jim's excellent answer: Ada got it right the first time,
>> back in 1980.
>
> So, if I write a, say, linear equation solver using generics in Ada,
> and then instantiate it with single precision, double precision,
> complex number single precision and complex number double precision,
> you'd expect it to be as fast as the equivalent non-generic versions?

Yes, exactly.  The language allows that, and also allows the compiler
to share the object code for generics (which incurs indirection
overhead).  In practice, only one compiler shares generics while all
others will emit different (and differently optimized) object code for
each instance.

-- 
Ludovic Brenta.