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From: Gautier write-only <gautier_niouzes@hotmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Performance of the Streams 'Read and 'Write
Date: Fri, 30 Oct 2009 02:13:19 -0700 (PDT)
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On 30 Okt., 04:36, Georg Bauhaus <rm-host.bauh...@maps.futureapps.de>:

> I finally thought that the above procedures are faster than 'Read
> or 'Write because the latter are defined in terms of stream elements:
> When there is a composite object like b : Buffer and you
> 'Write it, then for each component of b the corresponding 'Write
> is called. This then writes stream elements, probably
> calling Stream_IO.Write or some such in the end.
> So Write from above appears closer to writing bulk loads
> of stream elements than a bulk load of 'Writes can be.

Sure, it is the safe way: write records field by field, arrays element
by element (that recursively). The compiler avoids problems with non-
packed data. Nothing against that. The general case is well done,
fine. But the compiler could have a look a the type left to the
attribute and in such a case (an array of Unsigned_8, or a String)
say: "Gee! that type Buffer is coincidentally the same as
Stream_Element_Array, then I take the shortcut to generate the code to
write the whole buffer and, this time, not the code to write it
element by element".

> Copying buffers does not matter in comparison to the needs of I/O (on PCs).

Right. Variant 2 works fine, but it is an heavy workaround in terms of
source code. Especially for mixed type I/O with plenty of String'Write
and others, you would not want to put the kind of Variant 2 code all
over the place. It  would be a lot better that compilers are able to
take selectively the shortcut form for the attributes.

Gautier