[R] odd feature

[Martin Maechler]

>>>>> "Gabor" == Gabor Grothendieck <ggrothendieck at gmail.com>
>>>>>     on Mon, 22 May 2006 11:34:09 -0400 writes:

    Gabor> On 5/22/06, Martin Maechler <maechler at stat.math.ethz.ch> wrote:
    >> >>>>> "TL" == Thomas Lumley <tlumley at u.washington.edu>
    >> >>>>>     on Mon, 22 May 2006 07:09:09 -0700 (PDT) writes:
    >> 
    TL> On Mon, 22 May 2006, Gabor Grothendieck wrote:
    >> >> Due to lazy evaluation, I don't think a and b are fully evaluated:
    >> >>
    >> >>> ifelse(1, a <- 1, b <- 2)
    >> >> [1] 1
    >> >>> a
    >> >> [1] 1
    >> >>> b
    >> >> Error: object "b" not found
    >> 
    TL> yes. If you look at the code for ifelse() it evaluates
    TL> the second argument if any test values are TRUE and the
    TL> third argument if any test values are FALSE, so in the
    TL> scalar case it does not evaluate both arguments.
    >> 
    >> yes.
    >> And (Gabor), if you recall what I said earlier,  it's pretty clear
    >> that I would not even *consider* using ifelse() in the scalar
    >> case.  So my original statement was about the case ifelse() is
    >> designed for: The non-trivial vector case, and there my
    >> statement of "fully evaluated"  does apply.
    >> 
    >> Martin
    >> 

    Gabor> I don't think they are fully evaluated in the vector case either:

    >> ifelse(rep(TRUE,4), a <- 1:4, b <- 1:4)
    Gabor> [1] 1 2 3 4
    >> a
    Gabor> [1] 1 2 3 4
    >> b
    Gabor> Error: object "b" not found

PLEASE !!!!
------

I said  "non-trivial"  above !!!!!!!!
Martin