R Tips: ":::" "::"

For a package pkg, pkg::name returns the value of the exported variable name in namespace pkg, whereas pkg:::name returns the value of the internal variable name. The package namespace will be loaded if it was not loaded before the call, but the package will not be attached to the search path.

Specifying a variable or package that does not exist is an error.

Note that pkg::name does not access the objects in the environment package:pkg (which does not exist until the package's namespace is attached): the latter may contain objects not exported from the namespace. It can access datasets made available by lazy-loading.

• 一句话两个冒号的函数是供你调用的，三个冒号的函数是供两个冒号的函数调用的。