Safely get the attribute of an object. An error is given if the attribute does not exist (and do.stop = TRUE)
Arguments
- x
object from which to take the attribute
- attributeName
name of the attribute to be returned
- do.stop
if
TRUE(default) an error is raised if the attribute does not exist.
Examples
x <- structure(1, a = 2)
# getAttribute(x, "b") # gives a clear error message
identical(getAttribute(x, "a"), attr(x, "a")) # is TRUE
#> [1] TRUE
# Get an attribute's attribute by means of a "path" notation
y <- structure(1, a = structure(2, b = 3))
z <- structure(4, y = y)
str(y)
#> num 1
#> - attr(*, "a")= num 2
#> ..- attr(*, "b")= num 3
str(z)
#> num 4
#> - attr(*, "y")= num 1
#> ..- attr(*, "a")= num 2
#> .. ..- attr(*, "b")= num 3
kwb.utils::getAttribute(y, "a/b")
#> [1] 3
kwb.utils::getAttribute(z, "y/a/b")
#> [1] 3