Re: for S'Image use Func??

[Warren <ve3wwg@gmail.com>]

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Dmitry A. Kazakov expounded in news:1qfu2ba65pd63$.asc7m201hi6u$.dlg@
40tude.net:

> On Tue, 11 May 2010 17:17:38 +0000 (UTC), Warren wrote:
> 
>> =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?= =?utf-8?Q?=29?= expounded 
in
>> news:op.vcig7go1ule2fv@garhos: 
>> 
>>> Le Mon, 10 May 2010 22:56:11 +0200, Maciej Sobczak  
>>> <see.my.homepage@gmail.com> a écrit:
>>>> Coming back to I/O - what I miss in Ada is the equivalent of fread 
in
>>>> C - that is, an operation that reads *up to* the given number of
>>>> bytes. Or maybe there is something that I didn't notice?
>> 
>>> It's there : look at [ARM 2005 13.13.1] which defines the package  
>>> Ada.Streams, which in turn contains the following :
>>> 
>>>     type Root_Stream_Type is abstract tagged limited private;
>>>     ...
>>>     type Stream_Element is mod implementation-defined;
>>>     ...
>> ...
>>> Well, to be honest, this is not exactly the same as with C, as  
>>> Ada.Streams.Stream_Element is implementation defined (which is good,  
>>> because this is indeed platform dependent), so you will need ..
>> 
>> All this is well and good for applications that can work in 
>> "implementation defined" units of type Stream_Element. A pragma
>> won't fix the problem should it be different than a byte. Granted,
>> it will never likely come up on the platforms I have in mind.
> 
> If you to read a character stream, just do so:
> 
>    Item := Character'Read (S);
>    Character'Write (S, Item);
> 
> For octet streams use Unsigned_8.

But this has to include seeking in the stream as well.

Can you guarantee seeking to an arbitrary "byte boundary"?
I'm asking because I'm too lazy right now to look it up.
But IIRC, the best you can do is the Ada.Streams.Stream_Element.

Warren