dbConnectionInfo {Rdbi} | R Documentation |
dbConnectionInfo
is a generic function that, when called on a
valid connection object, returns a list containing connection status
information. It is called by print.Rdbi.conn
.
dbConnectionInfo(conn)
conn |
A database connection object. |
Any useful information such as the database host and connection status should be returned.
An arbitrary list of connection attributes.
I should probably define a dbConnectionOK
method that is
generic and return TRUE
when the connection is valid. However,
you don't need to constantly check for a valid connection object. Keep
the code path short! For example, in Rdbi.PgSQL, there is a C function
that submits a query request to the database backend. This is the only
time that the connection object is actually derefenced to its connection
pointer. This C function checks for a valid connection and returns and
error if needed. Therefore there is no reason to check whether the
connection is valid before passing it to a query function; the C code
will do the check. In this way the interface is simplified and the
connection checking is localized to a single call instead of scattered
all over the code. As Bertrand Meyer put it: "Defensive coding is
offensive!".
Timothy H. Keitt
dbConnect
,
dbDisconnect
,
methods, class