R | Inspecting object internals

R has a (not well undocumented) function that allows one to inspect some internal information of objects, which can be useful for debugging.

This is the form:

.Internal(inspect(x, max.depth=-1, max.elements=5))

This will display information about x, typically in a nested fashion for composite values.

• max.depth is the maximum nesting depth level that will be displayed; setting -1 will display all levels

• max.elements is the maximum number of elements per level that will be displayed; any element after that will not be printed out

Example Output:

> .Internal(inspect(c("foo", "bar")))@7fafbe061708 16 STRSXP g0c2 [] (len=2, tl=0)  @7fafb61d46e0 09 CHARSXP g1c1 [MARK,gp=0x61,ATT] [ASCII] [cached] "foo"  @7fafb8e7d100 09 CHARSXP g0c1 [gp=0x60,ATT] [ASCII] [cached] "bar"

See [1] for more information on the usage of this function.

Resources:

• [1] https://www.brodieg.com/2019/02/18/an-unofficial-reference-for-internal-inspect/