[R] Completion for custom "$" operator?

Romain Francois romain.francois at dbmail.com
Fri Aug 7 09:44:07 CEST 2009


On 08/07/2009 09:38 AM, Deepayan Sarkar wrote:
> On 8/7/09, Romain Francois<romain.francois at dbmail.com>  wrote:
>> On 08/04/2009 10:02 PM, Deepayan Sarkar wrote:
>>
>>> On Tue, Aug 4, 2009 at 11:37 AM, Vitalie S.<vitosmail at rambler.ru>   wrote:
>>>
>>>> Dear UseRs,
>>>>
>>>> I declared a `$` method for a S4 class. Can I have ab automatic
>> completion
>>>> for this operator in R? Lists and environment objects provide this
>> feature
>>>> by default, but my object is an extension of "function" class which does
>> not
>>>> have subseting defined. How to be?
>>>>
>>> Completion should be automatic if you define names() to return the valid
>> names.
>>> -Deepayan
>>>
>>   Hi,
>>
>>   Shouldn't this be delegated to a custom method. ie :
>>
>>   complete<- function( x, ... ){
>>          UseMethod( "complete" )
>>   }
>>   complete.default<- function( x, ... ){
>>          names( x )
>>   }
>>
>>   or maybe the equivalent S4 incantation.
>>
>>   This would separate the completion from the names, and therefore give more
>> flexibility to class writers.
>
> Ideally yes (although "complete" doesn't seem the best choice; this is
> only for $ completion). It's an easy enough change, and I'll be happy
> to make it if there's interest (and a use case where names() has good
> reason to be different).
>
> -Deepayan

The motivation for this was for java object references in rJava (jobjRef 
class). See this: http://tr.im/vQkf

Romain

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Romain Francois
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http://romainfrancois.blog.free.fr
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