[R-pkg-devel] failing S3 dispatch

[Jens Oehlschlägel]

Thank you Duncan,

bit NAMESPACE has

S3method(clone,default)
export(clone)

ff NAMESPACE has

import(bit)
# wish of CRAN maintainers: export another time here (now maintained and 
exported in bit)
# without this R CMD CHECK complained, but with it R CMD CHECK complains 
also, how to export again and why?
# clone
#,clone.default
  clone.ff
,clone.ffdf
S3method("clone",ff)
S3method(clone, ffdf)
# wish of CRAN maintainers: export another time here (now maintained and 
exported in bit)
#S3method(clone, default)

Best

Jens



On 20.10.21 11:02, Duncan Murdoch wrote:
> On 19/10/2021 3:43 p.m., Jens Oehlschlägel wrote:
>> I didn't find an answer elsewhere:
>>
>> My package 'bit' creates a S3 generic 'clone' and exports it.
>> Furthermore it registers a S3 method 'clone.default' (not exported).
>>
>> My package 'ff' imports package 'bit' and exports and registers a new S3
>> method 'clone.ff'. However, calling 'clone(ffobj)' dispatches to
>> clone.default instead of clone.ff !? Why?
>
> You should show us the NAMESPACE entries involving clone and clone.ff 
> from ff.
>
> Some comments that may or may not be relevant:
>
>  - Normally you wouldn't export clone.ff, it's enough to register it 
> using S3method().
>
>  - You may have created a new generic named clone, and that's what 
> clone.ff would attach itself to.  You can have bit::clone and 
> ff::clone as different generics and that would cause problems.
>
>>
>> What is the recommended way to create new S3-methods that get
>> dispatched? In earlier versions of the packages I simply exported
>> everything - that worked.
>
> I import the generic and use S3method(generic, method).  I don't 
> export the methods, so I wouldn't be able to call z <- clone.ff(a).
>
> Duncan Murdoch
>
>>
>> Best
>>
>>
>> Jens
>>
>>
>>   > require(ff)
>>   >
>>   > a <- as.ff(0:9)
>>   > class(x)
>> [1] "ff_vector" "ff"
>>   >
>>   > x <- clone(a)
>>   > y <- bit:::clone.default(a)
>>   > z <- clone.ff(a)
>>   >
>>   > # cloned ffobjects should have different filenames>
>>
>>   > filename(a)  # original
>> [1] "/tmp/Rtmpk17JRZ/ff/clone1ed54cbb5060.ff"
>>   >
>>   > filename(x)  # unexpected equal (dispatch to clone.default)
>> [1] "/tmp/Rtmpk17JRZ/ff/clone1ed54cbb5060.ff"
>>   >
>>   > filename(y)  # expected equal
>> [1] "/tmp/Rtmpk17JRZ/ff/clone1ed54cbb5060.ff"
>>   >
>>   > filename(z)  # OK
>> [1] "/tmp/Rtmpk17JRZ/ff/clone1ed551d3ee66.ff"
>>
>>   > version
>>                  _
>> platform       x86_64-pc-linux-gnu
>> arch           x86_64
>> os             linux-gnu
>> system         x86_64, linux-gnu
>> status
>> major          4
>> minor          1.1
>> year           2021
>> month          08
>> day            10
>> svn rev        80725
>> language       R
>> version.string R version 4.1.1 (2021-08-10)
>> nickname       Kick Things
>>
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>>
>