R Under development (unstable) (2023-11-16 r85542 ucrt) -- "Unsuffered Consequences"
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> library("R.utils")
Loading required package: R.oo
Loading required package: R.methodsS3
R.methodsS3 v1.8.2 (2022-06-13 22:00:14 UTC) successfully loaded. See ?R.methodsS3 for help.
R.oo v1.25.0 (2022-06-12 02:20:02 UTC) successfully loaded. See ?R.oo for help.

Attaching package: 'R.oo'

The following object is masked from 'package:R.methodsS3':

    throw

The following objects are masked from 'package:methods':

    getClasses, getMethods

The following objects are masked from 'package:base':

    attach, detach, load, save

R.utils v2.12.3 successfully loaded. See ?R.utils for help.

Attaching package: 'R.utils'

The following object is masked from 'package:utils':

    timestamp

The following objects are masked from 'package:base':

    cat, commandArgs, getOption, isOpen, nullfile, parse, warnings

> 
> local <- Options()
> print(local)
[1] "Options: 0 options set."
> str(local)
Options:
 list()
> print(names(local))
NULL
> print(nbrOfOptions(local))
[1] 0
> print(getLeaves(local))
NULL
> 
> 
> # Query a missing option
> cex <- getOption(local, "graphics/cex")
> cat("graphics/cex =", cex, "\n")  # Returns NULL
graphics/cex = 
> 
> # Query a missing option with default value
> cex <- getOption(local, "graphics/cex", defaultValue=1)
> cat("graphics/cex =", cex, "\n")  # Returns NULL
graphics/cex = 1 
> 
> # Set option and get previous value
> oldCex <- setOption(local, "graphics/cex", 2)
> cat("previous graphics/cex =", oldCex, "\n")  # Returns NULL
previous graphics/cex = 
> 
> # Set option again and get previous value
> oldCex <- setOption(local, "graphics/cex", 3)
> cat("previous graphics/cex =", oldCex, "\n")  # Returns 2
previous graphics/cex = 2 
> 
> # Query a missing option with default value, which is ignored
> cex <- getOption(local, "graphics/cex", defaultValue=1)
> cat("graphics/cex =", cex, "\n")  # Returns 3
graphics/cex = 3 
> 
> # Query multiple options with multiple default values
> multi <- getOption(local, c("graphics/cex", "graphics/pch"), c(1,2))
> print(multi)
$`graphics/cex`
[1] 3

$`graphics/pch`
[1] 2

> 
> # Check existance of multiple options
> has <- hasOption(local, c("graphics/cex", "graphics/pch"))
> print(has)
graphics/cex graphics/pch 
        TRUE        FALSE 
> 
> # Get a subtree of options
> graphics <- getOption(local, "graphics")
> print(graphics)
$cex
[1] 3

> 
> # Get the complete tree of options
> all <- getOption(local)
> print(all)
$graphics
$graphics$cex
[1] 3


> 
> proc.time()
   user  system elapsed 
   0.29    0.12    0.42