From ripley at stats.ox.ac.uk  Mon Apr 17 17:09:42 2006
From: ripley at stats.ox.ac.uk (Prof Brian Ripley)
Date: Mon, 17 Apr 2006 16:09:42 +0100 (BST)
Subject: [Rd] slot named C
In-Reply-To: <4443AC79.9080801@bank-banque-canada.ca>
References: <444395BC.5020108@bank-banque-canada.ca>
	<Pine.LNX.4.64.0604171446130.3487@gannet.stats.ox.ac.uk>
	<4443A656.4060306@bank-banque-canada.ca>
	<Pine.LNX.4.64.0604171536450.5712@gannet.stats.ox.ac.uk>
	<4443AC79.9080801@bank-banque-canada.ca>
Message-ID: <Pine.LNX.4.64.0604171605410.6595@gannet.stats.ox.ac.uk>

On Mon, 17 Apr 2006, Paul Gilbert wrote:

>
>
> Prof Brian Ripley wrote:
>> On Mon, 17 Apr 2006, Paul Gilbert wrote:
>>
>>> Ok, but I'm surprised. I thought partial matching only happened for
>>> named arguments. I guess I've been lucky.
>>
>> Here C is named, so what did you mean?
>
> Now I guess I've really been confused. I thought named arguments in a
> function were the optional ones you named when you define the function
> (with name=default, so Class is not a named argument in the call to

All formal arguments _are_ named.  Some have defaults.  So the allowed 
forms are

name
name=default

> new). Are you saying the named arguments are the ones you name when you
> call the function?

That's the standard usage.  See the Blue Book pp.37-8 (and I reckon that 
the posting guide asked you to look that up for yourself: so please 
re-read it).

>
> Paul
>>
>> Partial matching happens for all arguments called by name, except for
>> those following ... in the formals.
>>
>>>
>>> Paul
>>>
>>> Prof Brian Ripley wrote:
>>>> It's an error in your usage  The args of new() are
>>>>
>>>>> args(new)
>>>> function (Class, ...)
>>>>
>>>> and what does 'C' match?  You need to name your arguments here.
>>>>
>>>> On Mon, 17 Apr 2006, Paul Gilbert wrote:
>>>>
>>>>> "C" appears to be an illegal name for a slot in an S4 class (example
>>>>> below).
>>>>
>>>> It is rather an example of something which does not work.
>>>>
>>>> foo <- new("testobj")
>>>> foo at C <- 2
>>>>
>>>> does, for example.
>>>>
>>>>> If this is a known limitation, and not a bug, it would be nice
>>>>> if it were caught by setClass.
>>>>>
>>>>> Paul Gilbert
>>>>>
>>>>>> setClass("testobj", representation ( C = "numeric"))
>>>>> [1] "testobj"
>>>>>> new("testobj", C= 2)
>>>>> Error in methodsPackageMetaName("C", name) :
>>>>>        'The name of the object (e.g,. a class or generic function) to
>>>>> find in the meta-data' must be a single string (got an object of class
>>>>> "numeric")
>>>>>
>>>>>> setClass("testobj", representation ( C. = "numeric"))
>>>>> [1] "testobj"
>>>>>> new("testobj", C.= 2)
>>>>> An object of class "testobj"
>>>>> Slot "C.":
>>>>> [1] 2
>>>>> ====================================================================================
>>>>>
>>>>>
>>>>>
>>>>> La version fran?aise suit le texte anglais.
>>>>>
>>>>> ------------------------------------------------------------------------------------
>>>>>
>>>>>
>>>>>
>>>>> This email may contain privileged and/or confidential
>>>>> inform...{{dropped}}
>>>>>
>>>>> ______________________________________________
>>>>> R-devel at r-project.org mailing list
>>>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>>>
>>>>>
>>>>
>>> ====================================================================================
>>>
>>>
>>> La version fran?aise suit le texte anglais.
>>>
>>> ------------------------------------------------------------------------------------
>>>
>>>
>>> This email may contain privileged and/or confidential
>>> inform...{{dropped}}
>>>
>>> ______________________________________________
>>> R-devel at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-devel
>>>
>>>
>>
> ====================================================================================
>
> La version fran?aise suit le texte anglais.
>
> ------------------------------------------------------------------------------------
>
> This email may contain privileged and/or confidential inform...{{dropped}}
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595


[Rd] slot named C
Prof Brian Ripley