zap() creates a sentinel object that indicates that an object should be removed. For instance, named zaps instruct env_bind() and call_modify() to remove those objects from the environment or the call.

The advantage of zap objects is that they unambiguously signal the intent of removing an object. Sentinels like NULL or missing_arg() are ambiguous because they represent valid R objects.

zap()

is_zap(x)

Arguments

x

An object to test.

Examples

# Create one zap object: zap()
#> <zap>
# Create a list of zaps: rep(list(zap()), 3)
#> [[1]] #> <zap> #> #> [[2]] #> <zap> #> #> [[3]] #> <zap> #>
rep_named(c("foo", "bar"), list(zap()))
#> $foo #> <zap> #> #> $bar #> <zap> #>