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Metadata checks - Check if a collection is empty

is_empty2.Rd

Is a collection object (see is_collection()) empty, i.e. has zero length? Similar to rlang::is_empty(), but yields an error for non-collections, including NULL by default.

Note that objects of type 'S4' and 'object' are not considered collections, even if they are 'filled' with slots/attributes.

Usage

is_empty2(x, null = FALSE)

Arguments

x

[any] An object to test.

null

[TRUE | FALSE] Should NULL be considered a collection? If false will error for NULL, else, will return TRUE.

Value

[TRUE | FALSE] The scalar result of the test.

Examples

is_empty2(list()) #> TRUE
#> [1] TRUE
is_empty2(list(1)) #> FALSE
#> [1] FALSE
is_empty2(list(NULL)) #> FALSE
#> [1] FALSE

is_empty2(character(0)) #> TRUE
#> [1] TRUE
is_empty2(letters) #> FALSE
#> [1] FALSE

# Only works for collections (see ?is_collection()):
try(is_empty2(sum))
#> Error in is_empty2(sum) : `x` is not a collection.
#> Error in is_empty2(sum) : `x` is not a collection.

# But can be made to work with NULL:
is_empty2(NULL, null = TRUE) #> TRUE
#> [1] TRUE