[ESS] feature request : completion of available packages name

[Deepayan Sarkar]

On Wed, Jan 4, 2017 at 1:52 AM, Martin Maechler
<maechler using stat.math.ethz.ch> wrote:
> On Tue, Jan 3, 2017 at 6:30 PM, Samuel BARRETO
> <samuel.barreto8 using gmail.com> wrote:
>> Hi,
>>
>> Do you think it would be difficult to add some kind of completion backend
>> to complete the package names when typing `library(` ?
>> I was thinking that the list of packages could be populated by calling
>> something like :
>>
>> names(installed.packages()[,2])
>>
>> But I don't know enough elisp to implement it myself…
>
> Don't do it the way Rstudio does (it has very slow startup time, in
> parts of its interface, because it not only wants to know the package
> names of all my many thousand packages in my dozen of libraries in
> .libPaths(), but it also want to prepare all the help pages ... or
> something close to that).
>
> More seriously: We do something like that already in ESS for quite a
> while now.... but I don't recall the details.
> You also may want to give more details about the kind of completion..
> notably as emacs / ESS have quite a few different completion
> possibilities, as we have been told recently here.

Try executing

rc.settings(ipck = TRUE)

in your R session or .Rprofile and see if it works. It should as long
as ESS uses R's completion mechanism.

It does require running installed.packages() to create the cache,
which can be slow the first time for large/NFS libraries, which is why
it's disabled by default.

-Deepayan