[Rd] surprising behaviour of names<-

Wacek Kusnierczyk Waclaw.Marcin.Kusnierczyk at idi.ntnu.no
Mon Mar 16 09:16:34 CET 2009


Berwin A Turlach wrote:
>
>> '*tmp*' = 0
>> `*tmp*`
>> # 0
>>
>> x = 1
>> names(x) = 'foo'
>> `*tmp*`
>> # error: object "*tmp*" not found
>>
>> `*ugly*`
>>     
>
> I agree, and I am a bit flabbergasted.  I had not expected that
> something like this would happen and I am indeed not aware of anything
> in the documentation that warns about this; but others may prove me
> wrong on this.
>   

hopefully.

>   
>> given that `*tmp*`is a perfectly legal (though some would say
>> 'non-standard') name, it would be good if somewhere here a warning
>> were issued -- perhaps where i assign to `*tmp*`, because `*tmp*` is
>> not just any non-standard name, but one that is 'obviously' used
>> under the hood to perform black magic.
>>     
>
> Now I wonder whether there are any other objects (with non-standard)
> names) that can be nuked by operations performed under the hood.  
>   

any such risk should be clearly documented, if not with a warning issued
each time the user risks h{is,er} workspace corrupted by the under-the-hood.


> I guess the best thing is to stay away from non-standard names, if only
> to save the typing of back-ticks. :)
>   

agree.  but then, there may be -- and probably are -- other such 'best
to stay away' things in r, all of which should be documented so that a
user know what may happen on the surface, *without* having to peek under
the hood.


> Thanks for letting me know, I have learned something new today.
>   

wow.  most of my fiercely truculent ranting is meant to point out things
that may not be intentional, or if they are, they seem to me design
flaws rather than features -- so that either i learn that i am ignorant
or wrong, or someone else does, pro bono.  hopefully.

vQ



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