env_poke: Poke an object in an environment

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

Poke an object in an environment

Description

env_poke() will assign or reassign a binding in env if create is TRUE. If create is FALSE and a binding does not already exists, an error is issued.

Usage

env_poke(env = caller_env(), nm, value, inherit = FALSE, create = !inherit)

Arguments

env	An environment.
nm	Name of binding, a string.
value	The value for a new binding.
inherit	Whether to look for bindings in the parent environments.
create	Whether to create a binding if it does not already exist in the environment.

Details

If inherit is TRUE, the parents environments are checked for an existing binding to reassign. If not found and create is TRUE, a new binding is created in env. The default value for create is a function of inherit: FALSE when inheriting, TRUE otherwise.

This default makes sense because the inheriting case is mostly for overriding an existing binding. If not found, something probably went wrong and it is safer to issue an error. Note that this is different to the base R operator ⁠<<-⁠ which will create a binding in the global environment instead of the current environment when no existing binding is found in the parents.

Value

The old value of nm or a zap sentinel if the binding did not exist yet.

See Also

env_bind() for binding multiple elements. env_cache() for a variant of env_poke() designed to cache values.

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