As said in the title: Why is there no such function? Or in a different way: What is the type of the function? When I type
lubridate package provides the methods
lubridate:::update.POSIXt(). Those functions are not exported into the namespace, but I assume that, by means of function overloading, they are invoked when
update() is applied to a
Date object when the lubridate library is loaded.
The help page
?lubridate:::update.POSIXt provides some information concerning the
update function within the
update.Date and update.POSIXt return a date with the specified elements updated. Elements not specified will be left unaltered. update.Date and update.POSIXt do not add the specified values to the existing date, they substitute them for the appropriate parts of the existing date.
## S3 method for class 'POSIXt'
update(object, ..., simple = FALSE)
The usage section and the examples in the help page indicate that these functions don't need to be addressed individually, as they are called by simply using
update() when the
lubridate library is loaded.
To inspect these functions one can type, e.g.,
lubridate:::update.POSIXt in the console (without passing arguments, and without the parentheses).