m4_comment([$Id: verbose.so,v 1.2 2006/11/17 17:44:12 bostic Exp $])

m4_ref_title(Upgrading m4_db Applications,
    Release 4.6: verbose output,,
    upgrade.4.6/full_election, upgrade.4.6/verb)

m4_p([dnl
When an error occurs in the m4_db library, an exception is thrown or an
error return value is returned by the interface.  In some cases,
however, the exception or returned value may be insufficient to
completely describe the cause of the error, especially during initial
application debugging.  Applications can configure m4_db for verbose
messages to be output when an error occurs, but it's a common cause of
confusion for new users that no verbose messages are available by
default.])

m4_p([dnl
In the m4_db 4.6 release, verbose messages are configured by default.
For the C and C++ APIs, this means the default configuration when
applications first create m4_ref(Db) or m4_ref(DbEnv) handles is as if
the m4_ref(dbenv_set_errfile) or m4_refT(dbh_set_errfile)s were called
with the standard error output (stderr) specified as the FILE *
argument.  Applications wanting no output at all can turn off this
default configuration by calling the m4_ref(dbenv_set_errfile) or
m4_refT(dbh_set_errfile)s with NULL as the FILE * argument.
Additionally, explicitly configuring the error output channel using any
of the m4_ref(dbenv_set_errfile), m4_ref(dbh_set_errfile),
m4_ref(dbenv_set_errcall), m4_ref(dbh_set_errcall),
m4_ref(dbenv_set_error_stream) or m4_refT(dbh_set_error_stream)s will
also turn off this default output for the application.])

m4_p([dnl
Applications which configure m4_db with any error output channel should
not require any changes.])

m4_p([dnl
Applications which depend on having no output from the m4_db library by
default, should be changed to call the m4_ref(dbenv_set_errfile) or
m4_refT(dbh_set_errfile)s with NULL as the FILE * argument.])

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