dbenv_cxx.so

berkeley db 4.6.21的源码。berkeley db是一个简单的数据库管理系统

m4_comment([$Id: dbenv_cxx.so,v 11.10 2000/12/01 17:59:32 bostic Exp $])

m4_ref_title(Upgrading m4_db Applications,
    Release 3.0: the DbEnv class for C++ and Java,,
    upgrade.3.0/value_set, upgrade.3.0/db_cxx)

m4_p([dnl
The DbEnv::appinit() method and two constructors for the DbEnv class are
gone.  There is now a single way to create and initialize the environment.
The way to create an environment is to use the new DbEnv constructor with
one argument.  After this call, the DbEnv can be configured with various
set_XXX methods.  Finally, a call to DbEnv::open is made to initialize
the environment.])

m4_p([dnl
Here's a C++ example creating a m4_db environment using the 2.X interface])

m4_indent([dnl
int dberr;
DbEnv *dbenv = new DbEnv();
m4_blank
dbenv-__GT__set_error_stream(&cerr);
dbenv-__GT__set_errpfx("myprog");
m4_blank
if ((dberr = dbenv-__GT__appinit("/database/home",
	NULL, DB_CREATE | DB_INIT_LOCK | DB_INIT_MPOOL)) != 0) {
    cerr __LT____LT__ "failure: " __LT____LT__ strerror(dberr);
    exit (1);
}])

m4_p([dnl
In the m4_db 3.0 release, this code would be written as:])

m4_indent([dnl
int dberr;
DbEnv *dbenv = new DbEnv(0);
m4_blank
dbenv-__GT__set_error_stream(&cerr);
dbenv-__GT__set_errpfx("myprog");
m4_blank
if ((dberr = dbenv-__GT__open("/database/home",
	NULL, DB_CREATE | DB_INIT_LOCK | DB_INIT_MPOOL, 0)) != 0) {
    cerr __LT____LT__ "failure: " __LT____LT__ dbenv-__GT__strerror(dberr);
    exit (1);
}])

m4_p([dnl
Here's a Java example creating a m4_db environment using the 2.X interface:])

m4_indent([dnl
int dberr;
DbEnv dbenv = new DbEnv();
m4_blank
dbenv.set_error_stream(System.err);
dbenv.set_errpfx("myprog");
m4_blank
dbenv.appinit("/database/home",
    null, Db.DB_CREATE | Db.DB_INIT_LOCK | Db.DB_INIT_MPOOL);])

m4_p([dnl
In the m4_db 3.0 release, this code would be written as:])

m4_indent([dnl
int dberr;
DbEnv dbenv = new DbEnv(0);
m4_blank
dbenv.set_error_stream(System.err);
dbenv.set_errpfx("myprog");
m4_blank
dbenv.open("/database/home",
    null, Db.DB_CREATE | Db.DB_INIT_LOCK | Db.DB_INIT_MPOOL, 0);])

m4_p([dnl
In the m4_db 2.X release, DbEnv had accessors to obtain "managers" of type
DbTxnMgr, DbMpool, DbLog, DbTxnMgr.  If you used any of these managers,
all their methods are now found directly in the DbEnv class.])

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