From Kurt.Hornik at wu.ac.at  Fri Jun 12 13:16:23 2015
From: Kurt.Hornik at wu.ac.at (Kurt Hornik)
Date: Fri, 12 Jun 2015 13:16:23 +0200
Subject: [Rd] RFC: Declaring "foo.bar" as nonS3method() ?!
In-Reply-To: <557ABD04.1040205@gmail.com>
References: <000e01d0a387$885ad130$99107390$@mcmaster.ca>
	<21882.36966.429889.227076@stat.math.ethz.ch>
	<21882.37975.726216.982364@stat.math.ethz.ch>
	<557ABD04.1040205@gmail.com>
Message-ID: <21882.49031.599800.412740@fangorn.hornik.net>

>>>>> Duncan Murdoch writes:

> On 12/06/2015 4:12 AM, Martin Maechler wrote:
>> This is a topic ' "apparent S3 methods" note in R CMD check '
>> from R-package-devel  
>> https://stat.ethz.ch/pipermail/r-package-devel/2015q2/000126.html
>> 
>> which is relevant to here because some of us have been thinking
>> about extending R  because of the issue.
>> 
>> John Fox, maintainer of the 'effects' package has enquired about
>> the following  output from  'R CMD check effects' 
>> 
>> >> * checking S3 generic/method consistency ... NOTE
>> >> Found the following apparent S3 methods exported but not registered:
>> >> all.effects
>> 
>> and added
>> 
>> >> The offending function, all.effects(), is deprecated in favour of
>> >> allEffects(), but I'd rather not get rid of it for backwards compatibility.
>> >> Is there any way to suppress the note without removing all.effects()? 
>> 
>> and I had agreed that this was a "False Positive" in this case.
>> 
>> [.......]
>> 
>> and then
>> 
>> > Now I agree .. and have e-talked about this with another R core
>> > member .. that it would be desirable for the package author to
>> > effectively declare the fact that such a function is not an S3
>> > method even though it "looks like it" at least if looked from far.
>> 
>> > So, ideally, you could have something like
>> 
>> > nonS3method("all.effects")
>> 
>> > somewhere in your package source ( in NAMESPACE or R/*.R )
>> > which would tell the package-checking code -- but *ALSO* all the other S3
>> > method code that  all.effects should be treated as a regular R
>> > function.
>> 
>> > I would very much like such a feature in R, and for that reason,
>> > I'm cross posting this (as one of the famous exceptions that
>> > accompany real-life rules!!) to R-devel.
>> 
>> and actually I did *not* cross post, but have now moved the
>> relevant part of the thread to  R-devel.
>> 

> It sounds like a good idea.  It's a nontrivial amount of work, because
> of the "all the other S3 method code" part.  There's the question of
> functions defined outside of packages:  presumably they are still S3
> methods, with no way to suppress that.

I am not sure this is the right solution: S3 dispatch will still occur
because we first look at foo.bar exports and then in the S3 registry,
afaicr (the "all the other S3 method code" part).

If we could move to only looking at the registry for dispatch, there
would be no need to declare situations where we should not dispatch on
foo.bar exports.

-k



[Rd] RFC: Declaring "foo.bar" as nonS3method() ?!
Kurt Hornik