[Bioc-devel] testing class and length of function args

[Hervé Pagès]

Hi Mike,

On 07/22/2015 04:13 PM, Michael Love wrote:
> it's slightly annoying to write
>
> foo <- function(x) {
>    if ( ! is.numeric(x) ) stop("x should be numeric")
>    if ( ! length(x) == 2 ) stop("x should be length 2")
>    c(x[2], x[1])
> }

That's a little bit kind of what stopifnot() is for:

   stopifnot(is.numeric(x) && length(x) == 2)

The error message you get is not perfect English but is very concise:

   > foo(letters)
   Error: is.numeric(x) && length(x) == 2 is not TRUE

H.

>
> i wonder if we could have some core functions that test the class and
> the length in one and give the appropriate stop message.
>
> maybe this exists already
>
> -Mike
>
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-- 
Hervé Pagès

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