[Rcpp-devel] Odd-seeming behaviour of [[ and $

[Romain Francois]

Le 22/10/12 11:17, North, Ben a écrit :
> Hi Romain,
>
> Thanks for the reply.
>
>>> The fact that 'x[["value"]]' finds the method only if I've first done
>>> 'x$value' seemed odd.
>>
>> This is an implementation artefact. In short, you are not supposed to
>> use [[.
>
> OK, fair enough :)
>
> Because `$` doesn't evaluate its field-name argument, is
>
>      field.name <- "value"
>      do.call(`$`, list(x, field.name))
>
> the recommended way of accessing methods whose names are computed at
> run-time?  It does work; just wondering if there's a better way.
>
> Thanks,
>
> Ben.

I don't have anything else for you.

At this stage, I would however ask myself "do I __really__ need this at 
runtime ?"

Romain

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