R: Examples for 'rlang::vector-coercion'

### ** Examples

# Coercing atomic vectors removes attributes with both base R and rlang:
x <- structure(TRUE, class = "foo", bar = "baz")
as.logical(x)

[1] TRUE

# But coercing lists preserves attributes in base R but not rlang:
l <- structure(list(TRUE), class = "foo", bar = "baz")
as.list(l)

[[1]]
[1] TRUE

attr(,"class")
[1] "foo"
attr(,"bar")
[1] "baz"

as_list(l)

Warning: `as_list()` is deprecated as of rlang 0.4.0
Please use `vctrs::vec_cast()` instead.
This warning is displayed once every 8 hours.

Warning: `switch_type()` is soft-deprecated as of rlang 0.4.0.
Please use `switch(typeof())` or `switch(my_typeof())` instead.
This warning is displayed once every 8 hours.

[[1]]
[1] TRUE

# Implicit conversions are performed in base R but not rlang:
as.logical(l)

[1] TRUE

## Not run: 
##D as_logical(l)
## End(Not run)

# Conversion methods are bypassed, making the result of the
# coercion more predictable:
as.list.foo <- function(x) "wrong"
as.list(l)

[1] "wrong"

as_list(l)

[[1]]
[1] TRUE

# The input is never parsed. E.g. character vectors of numbers are
# not converted to numeric types:
as.integer("33")

[1] 33

## Not run: 
##D as_integer("33")
## End(Not run)


# With base R tools there is no way to convert an environment to a
# list without either triggering method dispatch, or changing the
# original environment. as_list() makes it easy:
x <- structure(as_environment(mtcars[1:2]), class = "foobar")
as.list.foobar <- function(x) abort("dont call me")
as_list(x)

$cyl
 [1] 6 6 4 6 8 6 8 4 4 6 6 8 8 8 8 8 8 4 4 4 4 8 8 8 8 4 4 4 8 6 8 4

$mpg
 [1] 21.0 21.0 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 17.8 16.4 17.3 15.2 10.4
[16] 10.4 14.7 32.4 30.4 33.9 21.5 15.5 15.2 13.3 19.2 27.3 26.0 30.4 15.8 19.7
[31] 15.0 21.4

Examples for 'rlang::vector-coercion'

Coerce an object to a base type