diff options
| author | Andy Wingo <wingo@pobox.com> | 2016-06-23 22:37:23 +0200 |
|---|---|---|
| committer | Andy Wingo <wingo@pobox.com> | 2016-06-23 22:37:23 +0200 |
| commit | 8a072fc2d628bc85c7edadc39d50b4ff3a00d6eb (patch) | |
| tree | f90ea06b505ab5587ede44c5f1940ef736894105 /doc | |
| parent | 498cd58cb43e0dde024ad3c62983def16a0c7ca9 (diff) | |
Add weak hash table documentation
* doc/ref/api-memory.texi (Weak hash tables): Update documentation.
Fixes #20551.
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/ref/api-memory.texi | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/doc/ref/api-memory.texi b/doc/ref/api-memory.texi index a2a27e43b..142eb0159 100644 --- a/doc/ref/api-memory.texi +++ b/doc/ref/api-memory.texi @@ -309,10 +309,18 @@ Return a weak hash table with @var{size} buckets. As with any hash table, choosing a good size for the table requires some caution. -You can modify weak hash tables in exactly the same way you -would modify regular hash tables. (@pxref{Hash Tables}) +You can modify weak hash tables in exactly the same way you would modify +regular hash tables, with the exception of the routines that act on +handles. Weak tables have a different implementation behind the scenes +that doesn't have handles. @pxref{Hash Tables}, for more on +@code{hashq-ref} et al. @end deffn +Note that in a weak-key hash table, the reference to the value is +strong. This means that if the value references the key, even +indirectly, the key will never be collected, which can lead to a memory +leak. The reverse is true for weak value tables. + @deffn {Scheme Procedure} weak-key-hash-table? obj @deffnx {Scheme Procedure} weak-value-hash-table? obj @deffnx {Scheme Procedure} doubly-weak-hash-table? obj |