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From: G. B. <nonlegitur@nmhp.invalid>
Newsgroups: comp.lang.ada
Subject: Re: stopping a loop iteration without exiting it
Date: Thu, 11 Jan 2018 20:54:45 -0000 (UTC)
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Date: 2018-01-11T20:54:45+00:00
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Dmitry A. Kazakov <mailbox@dmitry-kazakov.de> wrote:

>>> I have no idea what this is supposed to mean.
>> 
>> 
>> L:
>> [for|while...] loop
>> ...
>> goto L;
>> ...
>> end loop L;
>> 
>> Both outer Ls are part of what indicates the beginning
>> and end of the loop, resp. So, as others said in this thread,
>> there is syntactical ambiguity when using L with goto.
>> The meaning of the goto L is not clear or agreed upon
>> either, as readers here have said.
> 
> Substitute "exit" for "goto" and reread your text.

When writing, I also thought about “return” and about 
exceptions, not just about “exit”. But none of them has
the potential of driving the iterative process, they just
leave it, the building block. It will be over. 

loop is intended for the opposite, for when it’s not over yet.
For when it’s done again. “exit” cannot mean that, but the
hypothesized goto can.



>> A loop statement is a means of controlling flow. So is goto.
>> A loop controls iteration. Suppose that an additional
>> goto is needed to express that. Then this thread will
>> have discovered that Ada loops are deficient as building
>> blocks of iteration.
> 
> Substitute "if" for "goto".

Actually, “if” itself cannot directly make the program
iterate, unlike “goto”.