Wierd problem comparing numeric values and list using == (PR#1076)

gregory_r_warnes@groton.pfizer.com writes:

Under R 1.3.0 on Solaris and Windows NT  there seems to be a bug in == when
applied to elements of a list, particularly when one of the elements is of
mode integer:

      > list(1) == list(1)

      [1] FALSE

      > 1 == list(1)

      [1] TRUE

      > as.integer(1)==list(as.integer(1))

      [1] FALSE

      > as.integer(1)==list(as.double(1))

      [1] FALSE

      > list(as.integer(1))==list(as.integer(1))

      [1] FALSE

      > list(as.integer(1))==as.integer(1)

      [1] FALSE

      > list(as.double(1))==list(as.double(1))

      [1] FALSE

However, these cases work:

      > as.double(1)==list(as.integer(1))

      [1] TRUE

      > list(as.integer(1))==as.double(1)

      [1] TRUE

Replacing the bare integer/double with a vector constructed with c() doesn't
change the results, and comparing between vectors created with c() appears
correct.

It is not entirely clear what we *should* be doing here. S (-PLUS 3.4)
is at least consistent:

list(1) == list(1)

Error in list(1) == list(1): == operation on mode "list" undefined
Dumped

 1 == list(1)

Error in 1 == list(1): == operation on mode "list" undefined
Dumped

as.integer(1)==list(as.integer(1))

Error in as.integer(1) == list(as.integer(1)): == operation on mode "list"
        undefined
Dumped
...

so one might argue that you shouldn't do that in the first place...
(or that the bug is that we do not expressly forbid doing this.)

        -p

--
   O__  ---- Peter Dalgaard             Blegdamsvej 3
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907