[Rd] object.size vs lobstr::obj_size

[Stefan Schreiber]

I have posted this question on R-help where it was suggested to me
that I might get a better response on R-devel. So far I have gotten no
response. The post I am talking about is here:
https://stat.ethz.ch/pipermail/r-help/2020-February/465700.html

My apologies for cross-posting, which I am aware is impolite and I
should have posted on R-devel in the first place - but I wasn't sure.

Here is my question again:

I am currently working through Advanced R by H. Wickham and came
across the `lobstr::obj_size` function which appears to calculate the
size of an object by taking into account whether the same object has
been referenced multiple times, e.g.

x <- runif(1e6)
y <- list(x, x, x)
lobstr::obj_size(y)
# 8,000,128 B

# versus:
object.size(y)
# 24000224 bytes

Reading through `?object.size` in the "Details" it reads: [...] but
does not detect if elements of a list are shared [...].

My questions are:

(1) is the result of `obj_size()` the "correct" one when it comes to
actual size used in memory?

(2) And if yes, why wouldn't `object.size()` be updated to reflect the
more precise calculation of an object in question similar to
`obj_size()`?

There are probably valid reasons for this and any insight would be
greatly appreciated.