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Re: Hash-tables containing references to hash-tables


From: Pascal J. Bourguignon
Subject: Re: Hash-tables containing references to hash-tables
Date: Mon, 23 Nov 2009 15:10:44 +0100
User-agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/22.3 (darwin)

Nordlöw <address@hidden> writes:

> Is it possible for a hash-table to contain a *reference* to another
> hash-table, similar to how we can build arbitrary graphs using conses/
> lists and setf?

Yes.


There is not automatic copy ever done in lisp.  You have to
explicitely copy the structures (such as cons, copy-list,
copy-hash-table, copy-my-struct, etc) you use if you want copies (or
use a function that explicitely copies the input data like append does
for all lists but the last).  And for some types, there are even no
predefined copier function!  




-- 
__Pascal Bourguignon__


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