Experimental lifecycle

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.

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

Arguments

env

An environment.

nm

Names of bindings. nm must be a single 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.

Value

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

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.

Life cycle

env_poke() is experimental. We are still experimenting with reducing the number of redundant functions by using quasiquotation. It is possible env_poke() will be deprecated in favour of env_bind() and name-unquoting with :=.