Attaching/detaching R data files to an environment

While loading Rdata files, if we want to be notified whether objects with the same names already exist in the environment, we can use:

> attach("order.Rdata") 

The order.Rdata file contains an object named order. If an object named order already exists in the environment, we will get the following error:

The following object is masked _by_ .GlobalEnv: 
 
    order