Message-ID: <A71C9076-683F-43DE-8DD7-E94F67828806@dans.knaw.nl>
Date: 2018-08-30T14:01:25Z
From: Emil Bode
Subject: ROBUSTNESS: x || y and x && y to give warning/error if length(x) != 1 or length(y) != 1
In-Reply-To: <CAO1zAVYgQyKP3AbyB_AdTPKogWGQs=cC+YaTtLuG2OSahzvrVA@mail.gmail.com>
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 at r-project.org on behalf of jorismeys at gmail.com> wrote:
On Thu, Aug 30, 2018 at 2:09 PM D?nes T?th <toth.denes at 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
--
Joris Meys
Statistical consultant
Department of Data Analysis and Mathematical Modelling
Ghent University
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