using_config: Detect whether a configuration is currently active
Description
Environment-specific configuration values can be used to alter code's
behavior in different environments. The
config package uses the
R_CONFIG_ACTIVE environment variable to specify the active environment.
If R_CONFIG_ACTIVE is not set, the "default" configuration is used.
# See whether the default configuration is being usedusing_config("default")
# See whether the "production" configuration is being usedusing_config("production")