When I loaded package debug to debug a script with zoo objects, I got trouble: function index from zoo got masked by debug package. How can I unmask index? In general, how to deal with these name colliding problems? We just do not use debug package with `zoo'?
Exported symbols are always identifiable with the :: operator:
zoo::index
Hidden functions not declared in the namespace can still be accessed using ::: (triple-colon), and example would be
zoo:::.onLoad
which you can see even though it is not exported.
You can unload the package which has masked functions and then reload it. It will regain precedence in the searchpath:
unloadNamespace("zoo")
library("zoo")
In the future, if you want to load a package while preventing it from masking other functions, you can specify its position in the search path with an arbitrary large number:
library("debug", pos = .Machine$integer.max)
Its only masked to you but its not masked to zoo so when a zoo function tries to use index it will still find its own index first.
zoo also has a time.zoo method so if z is a zoo object you can use time(z) in place of index(z).
Finally you can always refer to zoo::index to make sure you get the one in zoo.
来源：https://stackoverflow.com/questions/3241539/how-to-unmask-a-function-in-r-due-to-name-collisions-on-searchpath