[R-SIG-Mac] UI suggestion: allow a tab with no more suggestions to fill in "$"

[Simon Urbanek]

If you don't see add.fn(), then use this instead which is equivalent:

RGUI = as.environment("tools:RGUI")
RGUI$rcompgen.completion <- function (x) {
comp <- function(x) {
     utils:::.assignLinebuffer(x)
     utils:::.assignEnd(nchar(x))
     utils:::.guessTokenFromLine()
     utils:::.completeToken()
     utils:::.CompletionEnv[["comps"]]
}
res <- unique(comp(x))
if (nzchar(x) && identical(res, x) && !identical(substr(x, nchar(x), nchar(x) + 1L), "$")) {
   rc <- comp(paste0(x, "$"))
   if (!identical(substr(rc, nchar(rc), nchar(rc) + 1L), "$")) res <- rc
}
res
}

Cheers,
Simon



> On May 31, 2016, at 4:12 AM, Timothy Bates <tim.bates at ed.ac.uk> wrote:
> 
> Hi all,
> Simon send code that would essentially allow users to customise the behavior in a very R-ish way. Perhaps someone could even release a package R.app.options to contain functions like this.
> 
> Code copied below: I can’t get it to work as add.fn doesn’t exist for me: no doubt soluble, as Simon says it’s loaded as part of the GUI-tools.
> 
> While there are a good many things I’d like in the R.app, I realise this is all stuff to create and maintain, so not requesting new preference pane items. So having this as custom code in a package to be launched at  startup would suffice.
> 
> re what to do about foo—> when foo$part and foolish both exist. My request was that the tab only do something when the current behavior does nothing. Alternatively, a hierarchial menu would solve this also:
> 
> foo$part
>     foolish
>     tile
> 
> A bundle storing options and executing a custom add.fn("rcompgen.completion", function (x)  would allow flexibility over some of these choice.
> 
> cheers,
> t
> 
>> "foo"  and "foolish" in your workspace?
>> You want to write  "foo$bar" , but which gets precedence when you enter
>> a tab?  "foo$bar" or "foolish” ?
> 
>> On 25 May 2016, at 12:51 pm, <cgw at witthoft.com> <cgw at witthoft.com> wrote:
>> I have to agree with Simon here that "best guess" will only lead to pain
>> in many cases.  
>> 
>> The best solution, albeit the most painful for Simon :-( , is to have a
>> Preferences pane where the user can specify what a tab does, i.e.
>> "nothing", " $", "@" , "$first_named_list_item", and so on.   But even
>> then, what if there are objects  "foo"  and "foolish" in your workspace?
>> You want to write  "foo$bar" , but which gets precedence when you enter
>> a tab?  "foo$bar" or "foolish" ?
>> 
>> [Tim wrote...]
>> 1. When a name is already complete, when the user pushes tab again, they
>> are expecting ?more? name completion, i.e.,  they want to access a $ or
>> @ sub-component. Currently, nothing happens, and the user feels
>> ?thwarted?? like the typing ?Simon" but then having to type a space and
>> a tab to get "Urbanek" :-)
>> 
>> 2. Most object components are $ indexed rather than @ indexed), so $ is
>> the best guess.
> 
> On 24 May 2016, at 10:08 pm, Simon Urbanek <simon.urbanek at r-project.org> wrote:
>> That seems like a very strong assumption and my point questioning that assumption. For a lot of objects $ makes no sense which is why I'm reluctant to add $ unconditionally. Really, it only makes sense for lists (and some subclasses) - anything else gets a bit dodgy (it works for some but not others).
>> 
>> That said, I suppose one possible approach would be to catch any completion that yields just the items itself and if that happens attempt a completion with $ appended and see what it yields. If it yields anything additional, return that result instead. You can test whether you like that by using something like the following:
>> 
> # add.fn is part of the GUI-tools which are automatically loaded when the R.app GUI starts
> # and rcompgen.completion what the GUI uses to call the completion code.
> 
> add.fn("rcompgen.completion", function (x) {
> comp <- function(x) {
>      utils:::.assignLinebuffer(x)
>      utils:::.assignEnd(nchar(x))
>      utils:::.guessTokenFromLine()
>      utils:::.completeToken()
>      utils:::.CompletionEnv[["comps"]]
> }
> res <- unique(comp(x))
> if (nzchar(x) && identical(res, x) && !identical(substr(x, nchar(x), nchar(x) + 1L), "$")) {
>    rc <- comp(paste0(x, "$"))
>    if (!identical(substr(rc, nchar(rc), nchar(rc) + 1L), "$")) res <- rc
> }
> res
> })
> 
> # Obviously, you can eve spin that further and carry on with @ if $ doesn't work.
> 
> 
> -- 
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