env_get: Get an object in an environment

In hadley/rlang: Functions for Base Types and Core R and 'Tidyverse' Features

Get an object in an environment

Description

env_get() extracts an object from an enviroment env. By default, it does not look in the parent environments. env_get_list() extracts multiple objects from an environment into a named list.

Usage

env_get(env = caller_env(), nm, default, inherit = FALSE, last = empty_env())

env_get_list(
  env = caller_env(),
  nms,
  default,
  inherit = FALSE,
  last = empty_env()
)

Arguments

env	An environment.
nm	Name of binding, a string.
default	A default value in case there is no binding for nm in env.
inherit	Whether to look for bindings in the parent environments.
last	Last environment inspected when inherit is TRUE. Can be useful in conjunction with base::topenv().
nms	Names of bindings, a character vector.

Value

An object if it exists. Otherwise, throws an error.

See Also

env_cache() for a variant of env_get() designed to cache a value in an environment.

Examples

parent <- child_env(NULL, foo = "foo")
env <- child_env(parent, bar = "bar")

# This throws an error because `foo` is not directly defined in env:
# env_get(env, "foo")

# However `foo` can be fetched in the parent environment:
env_get(env, "foo", inherit = TRUE)

# You can also avoid an error by supplying a default value:
env_get(env, "foo", default = "FOO")

hadley/rlang documentation built on Nov. 1, 2024, 4 p.m.