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From: eachus@spectre.mitre.org (Robert I. Eachus)
Newsgroups: comp.lang.ada
Subject: Re: Ada replacements for DOS I/O
Date: 3 Nov 94 09:24:26
Organization: The Mitre Corp., Bedford, MA.
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References: <44279.cwarwick@fox.nstn.ns.ca> <38qq4u$as2@theopolis.orl.mmc.com>
	<392r15$gl3@schonberg.cs.nyu.edu>
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In-reply-to: dewar@cs.nyu.edu's message of 31 Oct 1994 08:21:41 -0500
Date: 1994-11-03T09:24:26+00:00
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In article <392r15$gl3@schonberg.cs.nyu.edu> dewar@cs.nyu.edu (Robert Dewar) writes:

 > Of course simultaneous text_io from separate tasks to the same file (e.g.
 > standard output) is pretty hard to define anyway (at what level does the
 > output get interleaved - lines, text_io calls, characters, pixels?)

   Characters, Robert, characters. ;-)

   More seriously, chapter 14 is written to require, at worst, that
gets and puts of individual characters be treated as indivisible
actions.  Any reasonable tasking aware version of TEXT_IO can and
should lock at a higher level, but it is almost impossible to treat
Text_IO calls as atomic.  (For example, a read of a number can require
reading thousands of bytes from the external file.)

   When I've written tasking aware versions of Text_IO (usually by
revising the vendor supplied I/O routines and calling the result
Nice_IO or Tasking_IO), the locking granularity was either a line of
text or a text_io call, whichever was smaller.

--

					Robert I. Eachus

with Standard_Disclaimer;
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