[Rd] selectMethod() can fail to find methods in situations of multiple dispatch

[Michael Lawrence]

Agreed but I'm not sure we want users accessing documentation with those
types of aliases. One option is the method?foo("numeric") syntax.

On Thu, Mar 21, 2019 at 9:52 PM Pages, Herve <hpages using fredhutch.org> wrote:

> Fine with me as long as eliminating the inconveniences associated with it
> can be put on the roadmap. The alias instability and the fact that the user
> has no way to know if s/he should do ?`foo,numeric-method` or
> ?`foo,numeric,ANY-method` to find the method has been a long-standing
> problem.
>
> H.
> On 3/21/19 21:29, Michael Lawrence wrote:
>
> If we started over, I'd try to avoid this sort of complexity, but "ANY"
> truncation has been happening since at least 2003.
>
> > matchSignature(c("numeric", "ANY"), foo)
>         x
> "numeric"
>
> So I'm not sure we want to mess with it.
>
> Michael
>
> On Thu, Mar 21, 2019 at 8:14 PM Pages, Herve <hpages using fredhutch.org> wrote:
>
>> Hi Michael,
>>
>> Thanks for looking into this. I suspect that truncation of ANY suffixes
>> from method signatures is also the culprit behind the sudden breakage of
>> aliases of the form \alias{foo,numeric-method} when a method without the
>> ANY suffix in its signature gets added to the ecosystem. See my post about
>> this to the Bioc-devel mailing list a couple of months ago:
>> https://stat.ethz.ch/pipermail/bioc-devel/2019-January/014603.html
>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_pipermail_bioc-2Ddevel_2019-2DJanuary_014603.html&d=DwMFaQ&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=kjmNpPtpGtaMCrw8ubpy0siyz1xl8WY9gONjtL65IxE&s=R9Hi4Rm4nk-izYC8vDCj0NiuFdUMG4vZVbdQgsvxkDM&e=>
>>
>> So overall isn't this truncation more trouble than it's worth?
>>
>> H.
>> On 3/19/19 10:12, Michael Lawrence wrote:
>>
>> This is due to the intentional truncation of ANY suffixes from method
>> signatures. I've hacked selectMethod() to be robust to that and will commit
>> soon. Thanks for the report.
>>
>> Michael
>>
>> On Thu, Mar 14, 2019 at 9:32 AM Pages, Herve <hpages using fredhutch.org>
>> wrote:
>>
>>> Here is an example:
>>>
>>>   setGeneric("foo", function(x, y) standardGeneric("foo"))
>>>
>>>   setMethod("foo", c("numeric", "ANY"),
>>>     function(x, y) cat("I'm the foo#numeric#ANY method\n")
>>>   )
>>>
>>>
>>> Dispatch works as expected but selectMethod() fails to find the method:
>>>
>>>
>>>   > foo(1, TRUE)
>>>   I'm the foo#numeric#ANY method
>>>
>>>   > selectMethod("foo", c("numeric", "logical"))
>>>   Error in selectMethod("foo", c("numeric", "logical")) :
>>>     no method found for signature numeric, logical
>>>
>>> Adding an arbitrary method that doesn't have ANY in the signature
>>> "fixes" selectMethod():
>>>
>>>   setMethod("foo", c("complex", "integer"),
>>>     function(x, y) cat("I'm the foo#complex#integer method\n")
>>>   )
>>>
>>> Then:
>>>
>>>   > selectMethod("foo", c("numeric", "logical"))
>>>   Method Definition:
>>>
>>>   function (x, y)
>>>   cat("I'm the foo#numeric#ANY method\n")
>>>
>>>   Signatures:
>>>         x         y
>>>   target  "numeric" "logical"
>>>   defined "numeric" "ANY"
>>>
>>>
>>> Thanks,
>>>
>>> H.
>>>
>>>
>>> --
>>> Hervé Pagès
>>>
>>> Program in Computational Biology
>>> Division of Public Health Sciences
>>> Fred Hutchinson Cancer Research Center
>>> 1100 Fairview Ave. N, M1-B514
>>> P.O. Box 19024
>>> Seattle, WA 98109-1024
>>>
>>> E-mail: hpages using fredhutch.org<mailto:hpages using fredhutch.org>
>>> Phone:  (206) 667-5791
>>> Fax:    (206) 667-1319
>>>
>>>
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>>>
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>>> https://stat.ethz.ch/mailman/listinfo/r-devel
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>>>
>> --
>> Hervé Pagès
>>
>> Program in Computational Biology
>> Division of Public Health Sciences
>> Fred Hutchinson Cancer Research Center
>> 1100 Fairview Ave. N, M1-B514
>> P.O. Box 19024
>> Seattle, WA 98109-1024
>>
>> E-mail: hpages using fredhutch.org
>> Phone:  (206) 667-5791
>> Fax:    (206) 667-1319
>>
>> --
> Hervé Pagès
>
> Program in Computational Biology
> Division of Public Health Sciences
> Fred Hutchinson Cancer Research Center
> 1100 Fairview Ave. N, M1-B514
> P.O. Box 19024
> Seattle, WA 98109-1024
>
> E-mail: hpages using fredhutch.org
> Phone:  (206) 667-5791
> Fax:    (206) 667-1319
>
>

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