Feat request: assert_connection

[selkamand]

No description provided.

[selkamand]

There is no baseR 'connection' primitive/object. The most common connection objects are those created by the DBI package. These are S4 objects which inherit from the "DBIConnection" virtual class. My feeling is that these DBIConnection derived objects are ubiquitous enough that is_connection() could effectively be inherits(x, "DBIConnection"). We can add more class checks to is_connection() in the future if competing database interfacing packages roll their own connection class.