GNU bug report logs - #22737
25.1; Finalizer should be optional in dynamic modules

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From: Eli Zaretskii <eliz <at> gnu.org>
To: Jess Balint <jbalint <at> gmail.com>, Daniel Colascione <dancol <at> dancol.org>, John Wiegley <johnw <at> gnu.org> 
Cc: 22737 <at> debbugs.gnu.org
Subject: bug#22737: 25.1; Finalizer should be optional in dynamic modules
Date: Fri, 26 Feb 2016 23:33:07 +0200

> Date: Fri, 26 Feb 2016 12:53:20 -0600
> From: Jess Balint <jbalint <at> gmail.com>
> Cc: 22737 <at> debbugs.gnu.org
> 
>  What will happen if such objects are exposed to Lisp, copied or
>  assigned to other Lisp variables, etc.? Won't this cause all kinds of
>  trouble, like modifying one such object will magically modify several
>  others, which share its storage?
> 
> This is how C code works. If you return a pointer from a function, you may have to free that pointer yourself or
> you may not. You may get the same pointer back from multiple calls to the same function. If you use the
> pointer after it's been freed, it's your problem. You need to agree with the owner of the pointer how the
> memory is to be managed. With pointers, modifications to the underlying data are visible by all who have a
> pointer to the data. I wouldn't call this "magically modifying others".

In C, yes.  But we are talking about Lisp objects here.

Am I the only one who is uneasy with supporting such Lisp objects?  If
so, I will shut up and install the changes.  Daniel, John, what's your
opinion on this?

Thanks.

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