Create zap objects

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.

Usage

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>
#>