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Newsgroups: comp.lang.ada
Date: Tue, 13 Feb 2018 13:24:39 -0800 (PST)
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Subject: Re: troubles learning OOP: expected type "Parent.Some_Child", found
 type Parent'Class
From: Bojan Bozovic <bozovic.bojan@gmail.com>
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Xref: reader02.eternal-september.org comp.lang.ada:50432
Date: 2018-02-13T13:24:39-08:00
List-Id: <comp.lang.ada>

You didn't post p_expression.ads but posted body twice, and pastebin deleted most of your code. Consider Google drive, Dropbox or similar, just a single zip or tgz will be simpler than guessing why pastebin deleted your code.