Locked environments cannot be modified. An important example is namespace environments which are locked by R when loaded in a session. Once an environment is locked it normally cannot be unlocked.
Note that only the environment as a container is locked, not the
individual bindings. You can't remove or add a binding but you can
still modify the values of existing bindings. See
env_binding_lock() for locking individual bindings.
The old value of
# New environments are unlocked by default: env <- env(a = 1) env_is_locked(env)#>  FALSE# Use env_lock() to lock them: env_lock(env) env_is_locked(env)#>  TRUE# Now that `env` is locked, it is no longer possible to remove or # add bindings. If run, the following would fail: # env_unbind(env, "a") # env_bind(env, b = 2) # Note that even though the environment as a container is locked, # the individual bindings are still unlocked and can be modified: env$a <- 10