[Rd] utils::isS3stdGeneric chokes on primitives and identity

[Gabriel Becker]

Trace adds something to the body of the function, so it does make sense
that it doesn't. Whether traced functions still technically meet the
definition of standard s3 generic or not is, I suppose, up for debate, but
I would say that they should, I think.

As before, if desired I can work on a patch for this if desired, or someone
on R-core can just take care of it if that is easier.

Best,
~G

On Thu, Aug 27, 2020 at 11:22 AM Antoine Fabri <antoine.fabri using gmail.com>
wrote:

> Should it work on traced functions ?
>
> As it is now it doesn't.
>
> Best,
>
> Antoine
>
> Le jeu. 20 août 2020 à 09:58, Kurt Hornik <Kurt.Hornik using wu.ac.at> a écrit :
>
>> >>>>> Gabriel Becker writes:
>>
>> > I added that so I can look at the proposed fix and put it or something
>> > similar in bugzilla for review final review.
>>
>> > Apologies for the oversight.
>>
>> Fixed now with
>>
>> -    while(as.character(bdexpr[[1L]]) == "{")
>> +    while(is.call(bdexpr) && (as.character(bdexpr[[1L]]) == "{"))
>>
>> (the suggested fix does not work on things like
>> foo <- function(x) {{ x }}
>> ...)
>>
>> Best
>> -k
>>
>> > ~G
>>
>> > On Wed, Aug 19, 2020 at 3:40 PM Antoine Fabri <antoine.fabri using gmail.com>
>> > wrote:
>>
>> >> Dear R-devel,
>> >>
>> >> utils::isS3stdGeneric tries to subset the body of the function it's
>> fed,
>> >> primitives don't like that because they don't have a body, identity
>> doesn't
>> >> like it either because it's body is a symbol.
>> >>
>> >> According to the doc, any function is a legal input.
>> >>
>> >> See below:
>> >>
>> >> identity
>> >> #> function (x)
>> >> #> x
>> >> #> <bytecode: 0x0000000013d6da28>
>> >> #> <environment: namespace:base>
>> >>
>> >> max
>> >> #> function (..., na.rm = FALSE)  .Primitive("max")
>> >>
>> >> isS3stdGeneric(identity)
>> >> #> Error in bdexpr[[1L]]: objet de type 'symbol' non indiçable
>> >>
>> >> isS3stdGeneric(max)
>> >> #> Error in while (as.character(bdexpr[[1L]]) == "{") bdexpr <-
>> >> bdexpr[[2L]]: l'argument est de longueur nulle
>> >>
>> >> Here is a simple fix :
>> >>
>> >> isS3stdGeneric <- function(f) {
>> >> {
>> >> bdexpr <- body(f)
>> >> if(is.null(bdexpr) || !is.call(bdexpr)) return(FALSE)
>> >> while (as.character(bdexpr[[1L]]) == "{") bdexpr <- bdexpr[[2L]]
>> >> ret <- is.call(bdexpr) && identical(bdexpr[[1L]], as.name
>> >> ("UseMethod"))
>> >> if (ret)
>> >> names(ret) <- bdexpr[[2L]]
>> >> ret
>> >> }
>> >> }
>> >>
>> >> isS3stdGeneric(identity)
>> >> #> [1] FALSE
>> >> isS3stdGeneric(max)
>> >> #> [1] FALSE
>> >>
>> >> Best,
>> >>
>> >> Antoine
>> >>
>> >> [[alternative HTML version deleted]]
>> >>
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>> >>
>>
>> >       [[alternative HTML version deleted]]
>>
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>

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