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## Class: dbObjectId
## $Id$
## This package was developed as a part of Summer of Code program organized by Google.
## Thanks to David A. James & Saikat DebRoy, the authors of RMySQL package.
## Code from RMySQL package was reused with the permission from the authors.
## Also Thanks to my GSoC mentor Dirk Eddelbuettel for helping me in the development.
##
## This mixin helper class is NOT part of the database interface definition,
## but it is extended by the Oracle, MySQL,PostgreSQL and SQLite implementations
## to allow us to conviniently (and portably)
## implement all database foreign objects methods (i.e., methods for show(),
## print() format() the dbManger, dbConnection, dbResultSet, etc.)
## A dbObjectId is an identifier into an actual remote database objects.
## This class and its derived classes <driver-manager>Object need to
## be VIRTUAL to avoid coercion (green book, p.293) during method dispatching.
setClass("dbObjectId", representation(Id = "integer", "VIRTUAL"))
## coercion methods
setAs("dbObjectId", "integer",
def = function(from) as(slot(from,"Id"), "integer")
)
setAs("dbObjectId", "numeric",
def = function(from) as(slot(from, "Id"), "integer")
)
setAs("dbObjectId", "character",
def = function(from) as(slot(from, "Id"), "character")
)
## formating, showing, printing,...
setMethod("format", "dbObjectId",
def = function(x, ...) {
paste("(", paste(as(x, "integer"), collapse=","), ")", sep="")
},
valueClass = "character"
)
setMethod("show", "dbObjectId", def = function(object) print(object))
setMethod("print", "dbObjectId",
def = function(x, ...){
expired <- if(isPostgresqlIdCurrent(x)) "" else "Expired "
str <- paste("<", expired, class(x), ":", format(x), ">", sep="")
cat(str, "\n")
invisible(NULL)
}
)
## verify that obj refers to a currently open/loaded database
isPostgresqlIdCurrent <- function(obj) {
obj <- as(obj, "integer")
.Call(RS_DBI_validHandle, obj)
}
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