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

[Emil Bode]

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.
    
    c(TRUE,FALSE) || TRUE
    
    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.
    
    Cheers
    Joris
    
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