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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Use of expression function in protected type
Date: Wed, 21 Jan 2015 09:15:01 +0000
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Date: 2015-01-21T09:15:01+00:00
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Egil H H <ehh.public@gmail.com> writes:

> On Tuesday, January 20, 2015 at 11:34:54 PM UTC+1, Simon Wright wrote:
>> 9.4(8) says a protected_operation_item can be, inter alia, a
>> subprogram_declaration or a subprogram body. (subprogram_declaration?
>> how can that be?)
>
> Just like a package can have subprograms declared
> in the public part, private part or the body,
> protected subprograms can be declared in the public 
> part, private part or body of a protected type.
> (For example, it's not uncommon for a barrier 
> function to be declared in the body.)

One lives and learns! I've never had occasion to write a barrier
_function_; my most complex barrier was
   when A
     or else not B
     or else (C and then not (D and then E))

> However, an expression_function is allowed 
> to complete a subprogram_declaration, but is not
> itself a subprogram_declaration (ARM 6.1(30/3).
> As far as I can tell, it's a basic_declaration,
> which is allowed in package specifications and 
> bodies, but not in protected_operation_items.

That was my reading, but I wondered whether it was deliberate, an
oversight, or I'd missed something.

The context was Emacs ada-mode, whose indentation engine is built on a
parser, which follows the ARM.