m4_comment([$Id: callback.so,v 1.5 2000/10/26 15:20:40 bostic Exp $])

m4_ref_title(Upgrading m4_db Applications,
    [Release 3.2: DB callback functions, app_private field],,
    upgrade.3.2/set_flags, upgrade.3.2/renumber)

m4_p([dnl
In the m4_db 3.2 release, four application callback functions (the
callback functions set by m4_ref(dbh_set_bt_compare),
m4_ref(dbh_set_bt_prefix), m4_ref(dbh_set_dup_compare) and
m4_ref(dbh_set_h_hash)) were modified to take a reference to a
m4_ref(Db) object as their first argument.  This change allows the m4_db
Java API to reasonably support these interfaces.  There is currently no
need for the callback functions to do anything with this additional
argument.])

m4_p([dnl
C and C++ applications that specify their own Btree key comparison,
Btree prefix comparison, duplicate data item comparison or Hash
functions should modify these functions to take a reference to a
m4_ref(Db) structure as their first argument.  No further change is
required.])

m4_p([dnl
The app_private field of the m4_ref(Dbt) structure (accessible only from
the m4_db C API) has been removed in the 3.2 release.  It was replaced
with app_private fields in the m4_ref(DbEnv) and m4_ref(Db) handles.
Applications using this field will have to convert to using one of the
replacement fields.])

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