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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: strange cursor in nested containers
Date: Sat, 22 Apr 2023 04:33:37 -0500
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I agree. If you used a debugging container that checked for dangling 
cursors, you probably would have gotten an exception from any use of the 
cursor to the dead copy. Not sure that would have been any clearer as to the 
cause, but it would be a suggestion. (Not sure if GNAT still has debugging 
containers, they did at one point, but a lot of work has been done on them 
since.)

              Randy.

"Mario Blunk" <mario.blunk.gplus@gmail.com> wrote in message 
news:ed311a62-41ba-493e-a4cc-481402a1cc6bn@googlegroups.com...
Thanks for your replies. Now it is becoming clear to me:

1. The statement net : type_net renames element (n) gives a copy of element 
(n).
2. After the assignment to "result" (line 55), "result" points to an element 
inside the local copy "net".
3. Once "net" is overwritten in the next call of query_net, "result" still 
refers to a "net" that does not exist anymore. Likewise, once procedure 
query_net is left, "result" still points to a list that does not exist 
anymore. Thatswhy I get garbage in line 68 and 77.
Correct ?