[R-pkg-devel] visible binding for '<<-' assignment

[Gábor Csárdi]

You can include Unicode strings in a package, either as data, or just
as character vectors. Or character vectors returned by functions. Many
packages do that. E.g. cli:::symbol_utf8$tick is Unicode (not
exported, but it could be).

The only restriction is that the source file must be ASCII, i.e. you
need to create these vectors with `\u` escapes. For example the tick
in cli is created like this:
https://github.com/r-lib/cli/blob/e3ca34656f5bb82df63bfc1c741e75acc79b13d9/R/symbol.R#L27

When you print it (e.g. with something like
`cat(cli:::symbol_utf8$tick)`) the proper Unicode character is
printed, as long as the platform supports it. E.g. on macOS:

❯ cli:::symbol_utf8$tick
[1] "✔"

Gabor

On Thu, Sep 3, 2020 at 11:26 PM Dan Zigmond <djz using shmonk.com> wrote:
>
> I get that, but these variables are created by the package. It's a data
> package so the whole point is to provide access to the data. I'm just
> trying to provide an option to make the data more readable since I can't
> include Unicode strings directly in the package. In other words, these
> variables (eg, pali_alphabet) will already exist when the user attaches the
> package – but is there a way I can tweak them after the package has been
> loaded?
>
>      Dan
>
> .
> --------------------------
> Dan Zigmond
> djz using shmonk.com
>
>
>
> On Thu, Sep 3, 2020 at 2:56 PM William Dunlap <wdunlap using tibco.com> wrote:
>
> > > Is there a reason that this slightly more explicit
> > > version [assign(envir=.GlobalEnv)] wouldn't work?
> >
> > https://cran.r-project.org/web/packages/policies.html
> > - Packages should not modify the global environment (user’s workspace).
> >
> > Bill Dunlap
> > TIBCO Software
> > wdunlap tibco.com
> >
> > On Thu, Sep 3, 2020 at 2:36 PM Ben Bolker <bbolker using gmail.com> wrote:
> > >
> > >   Is there a reason that this slightly more explicit version wouldn't
> > work?
> > >
> > > pali_string_fix <- function() {
> > >      assign("pali_alphabet",
> > stringi::stri_unescape_unicode(pali_alphabet),
> > >             .GlobalEnv)
> > > }
> > >
> > >
> > > On 9/3/20 5:25 PM, Dan Zigmond wrote:
> > > > Thanks, Gabor. I want these to be easily available to package users
> > though
> > > > – that's why they are in the package. So I would rather not "hide"
> > them in
> > > > a local environment. This is fundamentally a data package, so access to
> > > > this data is the primary point of installing it.
> > > >
> > > > Is there any other solution?
> > > >
> > > >       Dan
> > > >
> > > > .
> > > > --------------------------
> > > > Dan Zigmond
> > > > djz using shmonk.com
> > > >
> > > >
> > > >
> > > > On Thu, Sep 3, 2020 at 1:40 PM Gábor Csárdi <csardi.gabor using gmail.com>
> > wrote:
> > > >
> > > >> Store the cached data in an environment within the package:
> > > >>
> > > >> pali_data <- new.env(parent = emptyenv())
> > > >>
> > > >> pali_string_fix <- function() {
> > > >>    pali_data$alphabet <-
> > > >>       stringi::stri_unescape_unicode(pali_alphabet)
> > > >> ...
> > > >> }
> > > >>
> > > >> Gabor
> > > >>
> > > >> On Thu, Sep 3, 2020 at 9:33 PM Dan Zigmond <djz using shmonk.com> wrote:
> > > >>>
> > > >>> Hi, all. I am developing a package that includes some global
> > variables.
> > > >>> Because these are non-ASCII, I have escaped them. But then because
> > these
> > > >>> are difficult to read, I want to provide an easy way for users to
> > > >> unescape
> > > >>> all of them up front. Thus I have code like to create and save the
> > data
> > > >> in
> > > >>> global variables in one file:
> > > >>>
> > > >>> pali_vowels <-
> > > >>>    c("a", "\u0101", "i", "\u012b", "u", "\u016b", "e", "o")
> > > >>> pali_consonants <-
> > > >>>    c("k", "kh", "g", "gh", "\u1e45",
> > > >>>      "c", "ch", "j", "jh", "\u00f1",
> > > >>>      "\u1e6d", "\u1e6dh", "\u1e0d", "\u1e0dh", "\u1e47",
> > > >>>      "t", "th", "d", "dh", "n",
> > > >>>      "p", "ph", "b", "bh", "m",
> > > >>>      "y", "r", "l", "v", "s", "h", "\u1e37", "\u1e43")
> > > >>> pali_alphabet <-c(pali_vowels, pali_consonants)
> > > >>> use_data(pali_alphabet, overwrite = TRUE)
> > > >>>
> > > >>> and then I try to export a function like this in another file:
> > > >>>
> > > >>> pali_string_fix <- function() {
> > > >>>    pali_alphabet <<-
> > > >>>       stringi::stri_unescape_unicode(pali_alphabet)
> > > >>>    # Several more of these...
> > > >>>    }
> > > >>>
> > > >>> The idea is that users can run pali_string_fix() once when they load
> > the
> > > >>> package and then they won't need to deal with all the Unicode escape
> > > >>> sequences after that.
> > > >>>
> > > >>> However, this is getting rejected by the CRAN checks with the
> > message:
> > > >>>
> > > >>> * checking R code for possible problems ... [4s] NOTE
> > > >>> pali_string_fix: no visible binding for '<<-' assignment to
> > > >>>    'pali_alphabet'
> > > >>>
> > > >>> I'm guessing this is because the data and the function are defined in
> > > >>> different files, so even though those globals are defined by my
> > package,
> > > >>> that isn't obvious when the check is run on this code.
> > > >>>
> > > >>> Does anyone have advice for how to fix this?
> > > >>>
> > > >>>       Dan
> > > >>>
> > > >>> .
> > > >>> -------------------------
> > > >>> Dan Zigmond
> > > >>> djz using shmonk.com
> > > >>>
> > > >>>          [[alternative HTML version deleted]]
> > > >>>
> > > >>> ______________________________________________
> > > >>> R-package-devel using r-project.org mailing list
> > > >>> https://stat.ethz.ch/mailman/listinfo/r-package-devel
> > > >>
> > > >
> > > >       [[alternative HTML version deleted]]
> > > >
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