getPackageName: The Name associated with a Given Package

Description

The functions below produce the package associated with a particular environment or position on the search list, or of the package containing a particular function. They are primarily used to support computations that need to differentiate objects on multiple packages.

Usage

getPackageName(where, create = TRUE)
setPackageName(pkg, env)
packageSlot(object)
packageSlot(object) <- value

Arguments

where

the environment or position on the search list associated with the desired package.

object

object providing a character string name, plus the package in which this object is to be found.

value

the name of the package.

create

flag, should a package name be created if none can be inferred? If TRUE and no non-empty package name is found, the current date and time are used as a package name, and a warning is issued. The created name is stored in the environment if that environment is not locked.

pkg, env

make the string in pkg the internal package name for all computations that set class and method definitions in environment env.

Value

getPackageName returns the character-string name of the package (without the extraneous "package:" found in the search list).

packageSlot returns or sets the package name slot (currently an attribute, not a formal slot, but this may change someday).

setPackageName can be used to establish a package name in an environment that would otherwise not have one. This allows you to create classes and/or methods in an arbitrary environment, but it is usually preferable to create packages by the standard R programming tools (package.skeleton, etc.)

Details

Package names are normally installed during loading of the package, by the INSTALL script or by the library function. (Currently, the name is stored as the object .packageName but don't trust this for the future.)

Examples

Run this code

# NOT RUN {
## all the following usually return "base"
getPackageName(length(search()))
getPackageName(baseenv())
getPackageName(asNamespace("base"))
getPackageName("package:base")

# }