Get value of package option

Retrieves the value of an zephyr_option. The value is looked up in the following order:

1. User defined option: {pkgname}.{name}

2. System variable: R_{PKGNAME}_{NAME}

3. Value of default argument (if not NULL)

4. Default value defined with create_option()

And returns the first set value.

Usage

get_option(name, .envir = sys.function(which = -1), default = NULL)

Arguments

name

[character(1)] Name of the option

.envir

Environment in which the option is defined. Default is suitable for use inside your package.

default

default value to return if the option is not set. If NULL uses the default set with create_option().

Value

Value of the option

Details

Environment variables are always defined as character strings. In order to return consistent values the following conversions are applied:

1. If they contain a ";" they are split into a vector using ";" as the delimiter.

2. If the class of the default value is not character, the value is converted to the same class using the naive as.{class} function. E.g. conversions to numeric are done with as.numeric().

These conversions are simple in nature and will not cover advanced cases, but we should try to keep our options this simple.

Examples

# Retrieve the verbosity level option set by default in zephyr:
get_option(name = "verbosity_level", .envir = "zephyr")
#> [1] "verbose"

# Try to retrieve an unset option, which will return the default value:
get_option(
  name = "my_unset_option",
  .envir = "mypkg",
  default = "my_default_value"
)
#> [1] "my_default_value"