Re: [Rd] Bug or feature: using "ANY" as a generic field class (was: '[R] Is there a (virtual) class that all R objects inherit from?)

From: John Chambers <jmc_at_r-project.org>
Date: Mon, 06 Jun 2011 09:29:17 -0700

Should now behave as expected in r-devel and 2.13 patched, as of SVN 56045, June 4. (noted in the NEWS file.)

On 6/6/11 6:27 AM, Janko Thyson wrote:
> Thanks a lot for your reply and I'm sorry if I didn't make it quite
> clear what I expected, but you got it right:
>
> I'd simply like to see the same behavior for Reference Classes as for S4
> classes when extending classes with "ANY" fields as featured in the
> example below.
>
> > setClass("A", representation(x="ANY"))
> [1] "A"
> > setClass("B", contains="A", representation(x="character"))
> [1] "B"
> > new("B", x = "abc")
> An object of class "B"
> Slot "x":
> [1] "abc"
>
> Thanks for addressing this!
>
> Regards,
> Janko
>
> On 03.06.2011 19:13, John Chambers wrote:
>> Well, your mail is unclear as to what you expected, but there is one
>> bug shown by your example.
>>
>> The behavior of S4 classes is sensible, at least as far as the example
>> shows:
>>
>>
>> > setClass("A", representation(x="ANY"))
>> [1] "A"
>> > setClass("B", contains="A", representation(x="character"))
>> [1] "B"
>> > new("B", x=1:3)
>> Error in validObject(.Object) :
>> invalid class "B" object: invalid object for slot "x" in class "B":
>> got class "integer", should be or extend class "character"
>>
>> You couldn't expect the new() call to work, as the error message
>> clearly explains. A legitimate call does work:
>>
>> > new("B", x = "abc")
>> An object of class "B"
>> Slot "x":
>> [1] "abc"
>>
>> The reference classes should work the same way, but don't, as your
>> example shows.
>>
>> A <- setRefClass(
>> + Class="A",
>> + fields=list(
>> + .PRIMARYDATA="ANY"
>> + ),
>> + contains=c("VIRTUAL")
>> + )
>> > B <- setRefClass(
>> + Class="B",
>> + fields=list(
>> + .PRIMARYDATA="character"
>> + ),
>> + contains=c("A")
>> + )
>> Error in `insertFields<-`(`*tmp*`, value = "character") :
>> The overriding class("character") of field ".PRIMARYDATA" is not a
>> subclass of the existing field definition ("ANY")
>>
>> We'll fix that. And, yes, "ANY" is intended as a universal superclass,
>> but is usually not mentioned explicitly.
>>
>>
>> On 6/3/11 6:53 AM, Janko Thyson wrote:
>>> Dear list,
>>>
>>> I was wondering if you could help me out in clarifying something:
>>> Is it possible to use class "ANY" in slots/fields of formal classes
>>> if you
>>> a) do not want to restrict valid classes of that field and
>>> b) if you are making explicit use of class inheritance?
>>>
>>> It seems to work in simple scenarios but produces errors when class
>>> inheritance comes into play. So I was wondering if that's a feature or a
>>> bug.
>>>
>>> If using "ANY" is not the right way, I'd appreciate a pointer to how you
>>> can to this.
>>>
>>> See previous post with an example below.
>>>
>>> Regards,
>>> Janko
>>>
>>> On 06/03/2011 01:53 AM, Janko Thyson wrote:
>>>> On 31.05.2011 18:17, Martin Morgan wrote:
>>>>> On 05/30/2011 07:02 AM, Janko Thyson wrote:
>>>>>> Dear list,
>>>>>>
>>>>>> I would like to set one specific Reference Class field to be of an
>>>>>> arbitrary class. Is there a class that all R objects inherit from? I
>>>>>> thought that "ANY" was something like this, but obviously that's not
>>>>>> true:
>>>>>>
>>>>>>> inherits(1:3, "ANY")
>>>>>> [1] FALSE
>>>>>
>>>>> I can't speak to the implementation, but ANY functions as a base class
>>>>> in terms of slot / field assignment and inheritance, e.g.,
>>>>>
>>>>> setClass("A", representation(x="ANY"))
>>>>> new("A", x=1:3)
>>>>>
>>>>> Martin
>>>>
>>>> Hi Martin,
>>>>
>>>> sorry for the late response. The way you do it works. Yet, when you
>>>> declare dependencies more explicitly (contains=XY), then R
>>>> complains. Is
>>>> this a feature or a bug (with respect to the "less explicit" way
>>>> working
>>>> just fine)? See the example below:
>>>>
>>>> # S4
>>>> setClass("A", representation(x="ANY"))
>>>> new("A", x=1:3)
>>>>
>>>> setClass("A", representation(x="ANY"))
>>>> setClass("B", contains="A", representation(x="character"))
>>>> new("B", x=1:3)
>>>>
>>>> # Reference Classes
>>>> setRefClass(
>>>> Class="A",
>>>> fields=list(
>>>> .PRIMARYDATA="ANY"
>>>> ),
>>>> contains=c("VIRTUAL")
>>>> )
>>>> B<- setRefClass(
>>>> Class="B",
>>>> fields=list(
>>>> .PRIMARYDATA="character"
>>>> ),
>>>> contains=c("A")
>>>> )
>>>
>>> Bug, I'd say. Martin
>>>
>>>>
>>>> Regards,
>>>> Janko
>>>>>>
>>>>>> Regards,
>>>>>> Janko
>>>>>>
>>>>>> [[alternative HTML version deleted]]
>>>>>>
>>>>>> ______________________________________________
>>>>>> R-help_at_r-project.org mailing list
>>>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>>>> PLEASE do read the posting guide
>>>>>> http://www.R-project.org/posting-guide.html
>>>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>>
>>>>>
>>>
>>>
>>
>> ______________________________________________
>> R-devel_at_r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>
>
>
> --
> ------------------------------------------------------------------------
>
> *Janko Thyson*
> janko.thyson_at_ku-eichstaett.de <mailto:janko.thyson_at_ku-eichstaett.de>
>
> Catholic University of Eichstätt-Ingolstadt
> Ingolstadt School of Management
> Statistics and Quantitative Methods
> Auf der Schanz 49
> D-85049 Ingolstadt
>
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>
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