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Type checks - Determine object-oriented system of object

object_system.Rd

R has many object-oriented systems, including S3, S4, RC, R6, R.oo, S7, proto, and ggproto. This function determines to which of these an object belongs, extending the test done by sloop::otype().

If x fails is.object(), the function returns "base". x matches "S3" if it is an object but does not match any other system, so systems not implemented here will fall into that category.

is_system() tests if an object belongs to a specific system.

Usage

object_system(x)

is_system(x, system)

Arguments

x

[any] An object to test.

system

[character(1)] Object-oriented system to check for.

Value

  • [character(1)] For object_system(): the object-oriented system of x.

  • [TRUE | FALSE] For is_system(): The scalar result of the test.

Details

The implemented check is as below:

  1. If not is.object(), return "base".

  2. Else, if isS4(), return "RC" if is(x, "refClass"), else return "S4".

  3. Else, if inherits_any(x, "S7_object") and typeof(x) == "object" (as an additional safeguard), return "S7".

  4. Else, if inherits_any(x, "R6") and rlang::is_environment(), return "R6".

  5. Else, if inherits_any(x, "ggproto") and rlang::is_environment(),

  6. return "ggproto".

  7. Else, if inherits_any(x, "proto") and all(c(".super", ".that") %in% names(x)) and rlang::is_environment(), return "proto".

  8. Else, if inherits_any(x, "Object") and all(c(".env", "...modifiers", "...finalize") %in% names(attributes(x))) and is_logical(x, 1), return "R.oo".

Examples

object_system(1:10) #> "base"
#> [1] "base"

object_system(factor(letters)) #> "S3"
#> [1] "S3"

xs4 <- methods::setClass("my_s4_int", contains = "integer")(1:10)
object_system(xs4) #> "S4"
#> [1] "S4"

is_system(xs4, "S4") #> TRUE
#> [1] TRUE