search for: wrapper_integer_elt

...rapped compact integer seq is an ALTREP object, so `ALTREP(x)` returns true. But then it just calls the default method of returning NULL rather than calling the compact integer seq `Extract_subset()` method! This still "works" because it falls back to `INTEGER_ELT()` for which there is a `wrapper_integer_Elt()` method defined that will use the underlying compact seq's `integer_Elt()` method, but it is less efficient than it could be. My rough benchmarks show that in R 3.6.0 the subset benchmarks at the bottom of this message take 4ms on the compact seq, and 5ms on the wrapped compact seq. With a p...