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[Bug-mit-scheme] [bug #28370] hash tables should be strong unless explic


From: Taylor R. Campbell
Subject: [Bug-mit-scheme] [bug #28370] hash tables should be strong unless explicitly desired otherwise
Date: Mon, 21 Dec 2009 23:34:40 +0000
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URL:
  <http://savannah.gnu.org/bugs/?28370>

                 Summary: hash tables should be strong unless explicitly
desired otherwise
                 Project: MIT/GNU Scheme
            Submitted by: riastradh
            Submitted on: Mon 21 Dec 2009 23:34:39 GMT
                Category: runtime
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Suboptimal behavior
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                Keywords: 

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Details:

If one asks for a hash table, one should not get a weak hash table unless one
explicitly asked for it.  MAKE-EQ-HASH-TABLE and MAKE-EQV-HASH-TABLE currently
confusingly yield strong hash tables, as a consequence of which only a small
fraction of their uses in MIT Scheme actually needed key-weak hash tables,
while for a much large fraction, using key-weak hash tables was either
confusing or incorrect.  We can't change the semantics of these two procedures
immediately, however, because what they do now is what they have been
documented to do.

See discussion at
<http://lists.gnu.org/archive/html/mit-scheme-devel/2009-12/msg00032.html>. 
Use of MAKE-EQ-HASH-TABLE was eradicated from MIT Scheme in commit
da6830c165b2540d93d1e3f1b31b6f0470392868, replaced by use of the more specific
constructors MAKE-STRONG-EQ-HASH-TABLE and MAKE-WEAK-EQ-HASH-TABLE.




    _______________________________________________________

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