Package 'config'

Read configuration values. Always use as config::get().

Description

Read from the currently active configuration, retrieving either a single named value or all values as a list.

Usage

get(
  value = NULL,
  config = Sys.getenv("R_CONFIG_ACTIVE", "default"),
  file = Sys.getenv("R_CONFIG_FILE", "config.yml"),
  use_parent = TRUE
)

Arguments

value	Name of value (NULL to read all values)
config	Name of configuration to read from. Defaults to the value of the R_CONFIG_ACTIVE environment variable ("default" if the variable does not exist).
file	Configuration file to read from (defaults to "config.yml"). If the file isn't found at the location specified then parent directories are searched for a file of the same name.
use_parent	TRUE to scan parent directories for configuration files if the specified config file isn't found.

Details

For additional details see https://rstudio.github.io/config/.

Value

The requested configuration value (or all values as a list of NULL is passed for value).

A list, or vector, corresponding to the contents of the config file.

Warning - Do not attach the package using library(config)

We strongly recommend you use config::get() rather than attaching the package using library(config).

In fact, we strongly recommend you never use library(config).

The underlying reason is that the get() and merge() functions in {config} will mask these functions with the same names in base R.

See Also

is_active(), merge()

Examples

yaml <- "
default:
  trials: 5
  dataset: 'data-sampled.csv'

production:
  trials: 30
  dataset: 'data.csv'
"

get <- base::get



with_config(yaml, config::get())
with_config(yaml, config::get("trials"))

---

Test active configuration.

Description

Check whether a configuration is currently active.

Usage

is_active(config)

Arguments

config

Configuration name

Details

The name of the currently active configuration is read from the R_CONFIG_ACTIVE environment variable. If the variable is not defined then the "default" configuration is used.

To test for whether a configuration is active you should use the is_active() function rather than inspecting the environment variable directly (this is to so that tests remain valid if other means of specifying configurations are introduced in the future).

Value

Logical indicating whether the specified configuration is active

See Also

get()

---

Merge two configurations. Always use as config::merge().

Description

Merge one configuration into another recursively.

Usage

merge(base_config, merge_config)

Arguments

base_config	Configuration to merge values into
merge_config	Configuration to merge values from

Value

Configuration which includes the values from merge_config merged into base_config.

Warning - Do not attach the package using library(config)

We strongly recommend you use config::get() rather than attaching the package using library(config).

In fact, we strongly recommend you never use library(config).

The underlying reason is that the get() and merge() functions in {config} will mask these functions with the same names in base R.

See Also

get()

---

Run code using a temporary config file.

Description

This function takes inspiration from withr::with_envvar() and may be useful for testing purposes.

Usage

with_config(
  config_yml,
  code,
  .active_config = c(R_CONFIG_ACTIVE = "default"),
  .extra_env_vars = NULL
)

Arguments

config_yml	Either the path to a config file, or a character string representing a yaml configuration.
code	Code to execute in a temporary environment.
.active_config	Either a string representing a configuration, e.g. default, or a named character representing an environment variable, e.g. c(R_CONFIG_ACTIVE = "default").
.extra_env_vars	Additional environment variables to set.

Value

The result of running the code, after having temporarily set the necessary environment variables.

Examples

yaml <- '
default:
  db_name: dbase
  databases:
    db1: !expr paste0(db_name, "/one")
    db2: !expr paste0(db_name, "/two")

staging:
  staging_postfix: _staging
  db_name: dbase
  databases:
    db1: !expr paste0(db_name, staging_postfix, "/one")
    db2: !expr paste0(db_name, staging_postfix, "/two")
'

# Ensure that base::get() doesn't get masked, for tests on CRAN
get <- base::get

with_config(yaml, config::get() )
with_config(yaml, config::get("databases", config = "default") )
with_config(yaml, config::get("databases", config = "staging") )

config_file <- system.file("tests/testthat/config.yml", package = "config")
if (file.exists(config_file)) {
  with_config(config_file, config::get())
}

---