R devel - Oct 2010 - "$<-" fails (invalid subscript type 'language')

This might be just beyond of my understanding of how assignment works in R, but
the documentation does not say anything about:
> tv <- c(a="dsf", b="sss")
> tl <- list(232)
> `$<-`(tl, tv[[1]], "sdfdsfdsfsd")
Error: invalid subscript type 'language'

This happens even before the method is dispatched. I can not handle the
"name" argument in my S4 method, because it's not even entered.

Thanks,
Vitalie.

spinuvit.list at gmail.com (Vitalie S.) writes:
> This might be just beyond of my understanding of how assignment works in R,
but
> the documentation does not say anything about:
>
>> tv <- c(a="dsf", b="sss")
>> tl <- list(232)
>> `$<-`(tl, tv[[1]], "sdfdsfdsfsd")
> Error: invalid subscript type 'language'
>
I can partially solve this with do.call, but there is another problem. Quoted
expressions are evaluated during the assignment:

te <- new.env()
> tq <- quote(print("!!!!"))
> do.call("$<-", list(te, "aa", tq))
[1] "!!!!"

This is some weird do.call and $<- interaction. Does not happen with other
functions.
> This happens even before the method is dispatched. I can not handle the
> "name" argument in my S4 method, because it's not even
entered.
>
> Thanks,
> Vitalie.

On Oct 24, 2010, at 5:35 AM, Vitalie S. wrote:
>
> This might be just beyond of my understanding of how assignment  
> works in R, but
> the documentation does not say anything about:
>
>> tv <- c(a="dsf", b="sss")
>> tl <- list(232)
>> `$<-`(tl, tv[[1]], "sdfdsfdsfsd")
> Error: invalid subscript type 'language'
Are either of these what you should have done to get what it appears  
you were aiming for but didn't specify?

  `$<-`(tl, "sdfdsfdsfsd", tv[[1]])
# yields
[[1]]
[1] 232

$sdfdsfdsfsd
[1] "dsf"

 > `[<-`(tl, tv[[1]], "sdfdsfdsfsd")
[[1]]
[1] 232

$dsf
[1] "sdfdsfdsfsd"

The "$" operator does not evaluate the index whereas the "["
function
does. And the documentation is quite clear about that distinction.

-- 
David Winsemius.

>
> This happens even before the method is dispatched. I can not handle  
> the
> "name" argument in my S4 method, because it's not even
entered.
>
> Thanks,
> Vitalie.