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From: "Matthew Heaney" <mheaney@on2.com>
Newsgroups: comp.lang.ada
Subject: Re: How to avoid unreferenced objects (mutexes etc)
Date: Sat, 12 Jan 2002 17:04:59 -0500
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"Nick Roberts" <nickroberts@adaos.worldonline.co.uk> wrote in message
news:a1o2h1$sfe3f$5@ID-25716.news.dfncis.de...
> However, really, a much better design is like this:

No, because protected operations can't make blocking calls.

Note that all predefined I/O packages are "potentially blocking," which
means, for example, that you can't call Text_IO from inside a protected
object.

So you still need a semaphore-style type (as in the original post), to
handle the situation in which blocking calls are made inside a critical
section.  The technique shown using a Limited_Controlled type to
automatically seize and release the semaphore is a standard Ada95 idiom.