[Rd] Assignment in environment

Duncan Murdoch murdoch.duncan at gmail.com
Sun Feb 7 22:22:32 CET 2016


On 07/02/2016 9:15 AM, peter dalgaard wrote:
>
>> On 07 Feb 2016, at 14:46 , Duncan Murdoch <murdoch.duncan at gmail.com> wrot8[e:
>>
> [snippage]
>>
>> but in fact, this doesn't work:
>>
>> getValue(fn)[[1]] <- 3
>> Error in getValue(fn)[[1]] <- 3 : could not find function "getValue"
>>
>> I suspect this is a parser problem.
>
> Umm, no...
>
> The canonical semantics are that
>
> foo(x)[[....]] <- bar
>
> is internally converted to
>
> *tmp* <- foo(x)
> *tmp*[[....]] <- bar
> x <- `foo<-`(x, *tmp*)
>
> so both foo() and `foo<-` are required.
>

Yes, you're right.  I need more sleep.

Duncan Murdoch



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