[Rd] ROBUSTNESS: x || y and x && y to give warning/error if length(x) != 1 or length(y) != 1

Emil Bode emil@bode @ending from d@n@@kn@w@nl
Thu Aug 30 16:01:25 CEST 2018

Okay, I thought you always wanted to check the length, but if we can only check what's evaluated I mostly agree.

I still think there's not much wrong with how length-0 logicals are treated, as the return of NA in cases where the value matters is enough warning I think, and I can imagine some code like my previous example 'x==-1 || length(x)==0', which wouldn't need a warning.

But we could do a check for length being >1

Greetings, Emil

On 30/08/2018, 14:55, "R-devel on behalf of Joris Meys" <r-devel-bounces using r-project.org on behalf of jorismeys using gmail.com> wrote:

    On Thu, Aug 30, 2018 at 2:09 PM Dénes Tóth <toth.denes using kogentum.hu> wrote:
    > Note that `||` and `&&` have never been symmetric:
    > TRUE || stop() # returns TRUE
    > stop() || TRUE # returns an error
    Fair point. So the suggestion would be to check whether x is of length 1
    and whether y is of length 1 only when needed. I.e.
    would give an error and
    TRUE || c(TRUE, FALSE)
    would pass.
    Thought about it a bit more, and I can't come up with a use case where the
    first line must pass. So if the short circuiting remains and the extra
    check only gives a small performance penalty, adding the error could indeed
    make some bugs more obvious.
    Joris Meys
    Statistical consultant
    Department of Data Analysis and Mathematical Modelling
    Ghent University
    Coupure Links 653, B-9000 Gent (Belgium)
    Biowiskundedagen 2017-2018
    Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php
    	[[alternative HTML version deleted]]
    R-devel using r-project.org mailing list

More information about the R-devel mailing list