env_parent()
returns the parent environment of env
if called
with n = 1
, the grandparent with n = 2
, etc.
env_tail()
searches through the parents and returns the one
which has empty_env()
as parent.
env_parents()
returns the list of all parents, including the
empty environment. This list is named using env_name()
.
See the section on inheritance in env()
's documentation.
env_parent(env = caller_env(), n = 1) env_tail(env = caller_env(), last = global_env()) env_parents(env = caller_env(), last = global_env())
env | An environment. |
---|---|
n | The number of generations to go up. |
last | The environment at which to stop. Defaults to the global environment. The empty environment is always a stopping condition so it is safe to leave the default even when taking the tail or the parents of an environment on the search path.
|
An environment for env_parent()
and env_tail()
, a list
of environments for env_parents()
.
# Get the parent environment with env_parent(): env_parent(global_env()) #> <environment: package:rlang> #> attr(,"name") #> [1] "package:rlang" #> attr(,"path") #> [1] "/data/GHE/deployment/deployments/2021-11-29/renv/library/R-4.1/x86_64-pc-linux-gnu/rlang" # Or the tail environment with env_tail(): env_tail(global_env()) #> <environment: base> # By default, env_parent() returns the parent environment of the # current evaluation frame. If called at top-level (the global # frame), the following two expressions are equivalent: env_parent() #> <environment: 0x560eaebc58b0> env_parent(base_env()) #> <environment: R_EmptyEnv> # This default is more handy when called within a function. In this # case, the enclosure environment of the function is returned # (since it is the parent of the evaluation frame): enclos_env <- env() fn <- set_env(function() env_parent(), enclos_env) identical(enclos_env, fn()) #> [1] TRUE