EVOLUTION-MANAGER

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<table width="100%" summary="page for get_env {rlang}"><tr><td>get_env {rlang}</td><td style="text-align: right;">R Documentation</td></tr></table>

<h2>Get or set the environment of an object</h2>

<h3>Description</h3>

<p>These functions dispatch internally with methods for functions,
formulas and frames. If called with a missing argument, the
environment of the current evaluation frame is returned. If you
call <code>get_env()</code> with an environment, it acts as the identity
function and the environment is simply returned (this helps
simplifying code when writing generic functions for environments).
</p>

<h3>Usage</h3>

<pre>
get_env(env, default = NULL)

set_env(env, new_env = caller_env())

env_poke_parent(env, new_env)
</pre>

<h3>Arguments</h3>

<table summary="R argblock">
<tr valign="top"><td><code>env</code></td>
<td>
<p>An environment.</p>
</td></tr>
<tr valign="top"><td><code>default</code></td>
<td>
<p>The default environment in case <code>env</code> does not wrap
an environment. If <code>NULL</code> and no environment could be extracted,
an error is issued.</p>
</td></tr>
<tr valign="top"><td><code>new_env</code></td>
<td>
<p>An environment to replace <code>env</code> with.</p>
</td></tr>
</table>

<h3>Details</h3>

<p>While <code>set_env()</code> returns a modified copy and does not have side
effects, <code>env_poke_parent()</code> operates changes the environment by
side effect. This is because environments are
<a href="is_copyable.html">uncopyable</a>. Be careful not to change environments
that you don't own, e.g. a parent environment of a function from a
package.
</p>

<p><code><a href="quosure-tools.html">quo_get_env()</a></code> and <code><a href="quosure-tools.html">quo_set_env()</a></code> for versions of
<code><a href="get_env.html">get_env()</a></code> and <code><a href="get_env.html">set_env()</a></code> that only work on quosures.
</p>

<h3>Examples</h3>

<pre>
# Environment of closure functions:
fn &lt;- function() "foo"
get_env(fn)

# Or of quosures or formulas:
get_env(~foo)
get_env(quo(foo))

# Provide a default in case the object doesn't bundle an environment.
# Let's create an unevaluated formula:
f &lt;- quote(~foo)

# The following line would fail if run because unevaluated formulas
# don't bundle an environment (they didn't have the chance to
# record one yet):
# get_env(f)

# It is often useful to provide a default when you're writing
# functions accepting formulas as input:
default &lt;- env()
identical(get_env(f, default), default)

# set_env() can be used to set the enclosure of functions and
# formulas. Let's create a function with a particular environment:
env &lt;- child_env("base")
fn &lt;- set_env(function() NULL, env)

# That function now has `env` as enclosure:
identical(get_env(fn), env)
identical(get_env(fn), current_env())

# set_env() does not work by side effect. Setting a new environment
# for fn has no effect on the original function:
other_env &lt;- child_env(NULL)
set_env(fn, other_env)
identical(get_env(fn), other_env)

# Since set_env() returns a new function with a different
# environment, you'll need to reassign the result:
fn &lt;- set_env(fn, other_env)
identical(get_env(fn), other_env)
</pre>

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