[Rd] strange value in .Last.value
murdoch.duncan at gmail.com
Wed Jun 5 16:28:29 CEST 2013
On 05/06/2013 10:18 AM, Vitalie Spinu wrote:
> >> Duncan Murdoch <murdoch.duncan at gmail.com>
> >> on Wed, 5 Jun 2013 07:59:54 -0400 wrote:
> >> As I take it, it is. Thus, ess/orgmode -- which relies on .Last.value
> >> for results handling and does not expect that $visible element -- should
> >> adapt and ignore that explicitly?
> > I think you'll need to ask on the ESS list what the intentions are in this case.
> > The result of source() is a list with the value and visible entries. This has
> > been true "forever", it's not new behaviour. (It's unfortunate that this is not
> > clearly documented.)
> ESS recently switched to "source" for evaluation in order to preserve
> source references, and that ruins org-babel (a literate programming
> backend) that relies on .Last.value.
> Would a
> invisible(source('file.R', echo=TRUE)$value)
> be a reliable solution to the problem?
You can count on source()$value to return the last value computed in the
source() if there was one. If there were no expressions computed, the
value will be NULL, but NULL$value is also NULL, so perhaps that is good
enough for your purposes.
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