On 21/10/2021 1:23 p.m., Jens Oehlschlägel wrote:
Thanks Duncan,
I finally found the reason for the mysterious dispatch-failure: I had an
unwanted and unexported replicated definition of the 'clone' generic in
ff's namespace (a left-over).
I still don't understand how this prevented the proper dispatch since
the duplicate in ff's namespace it was *not* called. I further
experimented and *any* non-exported object matching the name of the
generic caused the problem. Scary, maybe worth a check!
Your NAMESPACE file contains
S3method("clone",ff)
When R installs your package, it has to figure out where "clone" lives.
You imported a copy of it from bit, and then overwrote that imported
copy with the replicated definition.
That created a new generic belonging to ff, and that's the one that your
clone.ff method was attached to.
When you called clone(x), you called the bit::clone generic which never
received the registration, so dispatch to clone.ff never happened.
It makes sense: you don't want a generic in one package to interfere
with an unrelated generic in another package that happens to have the
same name.
Duncan Murdoch
Anyhow, removing the non-exported object solved the problem.
Best regards
Jens
On 20.10.21 13:43, Jens Oehlschlägel wrote:
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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