Required arguments can be set via options. See
blpConnect and blpAuthenticate for details.
In addition, if options blpAutoConnect and/or
blpAutoAuthenticate are set to ‘TRUE’, a connection and/or
authentication is established in the .onAttach() function and
stored in the package environment. This effectively frees users from
having to explicitly create such objects. Of course, the user can also
call blpConnect and/or blpAuthenticate explicitly and
store the connection/authentication objects. These helper functions
look up the stored connection/authentications object and return them.
In case no connection has been established, an error message is shown.
In case no authentication has been established, NULL is returned.
(NULL is sufficent for Desktop API connections.)