On-demand Loading of Packages

Description

autoload creates a promise-to-evaluate autoloader and stores it with name name in .AutoloadEnv environment. When R attempts to evaluate name, autoloader is run, the package is loaded and name is re-evaluated in the new package's environment. The result is that R behaves as if file was loaded but it does not occupy memory.

.Autoloaded contains the names of the packages for which autoloading has been promised.

Usage

autoload(name, package, reset = FALSE, ...)
autoloader(name, package, ...)

.AutoloadEnv
.Autoloaded

Arguments

Value

This function is invoked for its side-effect. It has no return value.

See Also

delayedAssign, library

Examples

require(stats)
autoload("interpSpline", "splines")
search()
ls("Autoloads")
.Autoloaded

x <- sort(stats::rnorm(12))
y <- x^2
is <- interpSpline(x, y)
search() ## now has splines
detach("package:splines")
search()
is2 <- interpSpline(x, y+x)
search() ## and again
detach("package:splines")

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type 'license()' or 'licence()' for distribution details.

R is a collaborative project with many contributors.
Type 'contributors()' for more information and
'citation()' on how to cite R or R packages in publications.

Type 'demo()' for some demos, 'help()' for on-line help, or
'help.start()' for an HTML browser interface to help.
Type 'q()' to quit R.

> library(base)
> png(filename="/home/ddbj/snapshot/RGM3/R_rel/result/base/autoload.Rd_%03d_medium.png", width=480, height=480)
> ### Name: autoload
> ### Title: On-demand Loading of Packages
> ### Aliases: autoload autoloader .AutoloadEnv .Autoloaded Autoloads
> ### Keywords: data programming
> 
> ### ** Examples
> 
> require(stats)
> autoload("interpSpline", "splines")
> search()
[1] ".GlobalEnv"        "package:stats"     "package:graphics" 
[4] "package:grDevices" "package:utils"     "package:datasets" 
[7] "package:methods"   "Autoloads"         "package:base"     
> ls("Autoloads")
[1] "interpSpline"
> .Autoloaded
[1] "splines"
> 
> x <- sort(stats::rnorm(12))
> y <- x^2
> is <- interpSpline(x, y)
> search() ## now has splines
 [1] ".GlobalEnv"        "package:splines"   "package:stats"    
 [4] "package:graphics"  "package:grDevices" "package:utils"    
 [7] "package:datasets"  "package:methods"   "Autoloads"        
[10] "package:base"     
> detach("package:splines")
> search()
[1] ".GlobalEnv"        "package:stats"     "package:graphics" 
[4] "package:grDevices" "package:utils"     "package:datasets" 
[7] "package:methods"   "Autoloads"         "package:base"     
> is2 <- interpSpline(x, y+x)
> search() ## and again
 [1] ".GlobalEnv"        "package:splines"   "package:stats"    
 [4] "package:graphics"  "package:grDevices" "package:utils"    
 [7] "package:datasets"  "package:methods"   "Autoloads"        
[10] "package:base"     
> detach("package:splines")
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>