[R-SIG-Mac] Mac OS X tcltk/X11 issues

[Gábor Csárdi]

Hi John,

On Mon, Jul 14, 2014 at 8:12 PM, John Fox <jfox at mcmaster.ca> wrote:
> Dear Gabor,
>
> As I just explained, the problem isn't testing for X11, which I know how to do -- though capabilities("X11") is a bit better than what I suggested. The issue is specific to Mac OS X because the Windows implementation of R includes a Tcl/Tk that doesn't use X11, and I've never seen the problem on Linux.

actually, what I am saying is, that it is not specific to OSX. Some
(older, before 2012) OSX versions do include an X11 server, and some
Linux or other Unix installations do not.

I am not saying tcltk should not test for an X11 server, all I am
saying is that the test suggested below (based on the os and the
existence of a certain file) is not the best one.

If it turns out that there is no X11 server, and the os is OSX, then
indeed a dialog box could be displayed, see e.g. the one at
http://www.macrumors.com/2012/02/17/apple-removes-x11-in-os-x-mountain-lion-shifts-support-to-open-source-xquartz/

Best,
Gabor

> Best,
>  John
>
>> -----Original Message-----
>> From: Gábor Csárdi [mailto:csardi.gabor at gmail.com]
>> Sent: Monday, July 14, 2014 6:37 PM
>> To: Marc Schwartz
>> Cc: John Fox; urbanek at research.att.com; R-SIG-Mac
>> Subject: Re: [R-SIG-Mac] Mac OS X tcltk/X11 issues
>>
>> What's wrong with capabilities("X11")?
>>
>> I am not sure if teting for the OS, and especially for a particular X
>> server, installed in a particular directory, is a good idea, even if
>> it covers most of the _current_ installations.
>>
>> Gabor
>>
>> On Mon, Jul 14, 2014 at 6:13 PM, Marc Schwartz <marc_schwartz at me.com>
>> wrote:
>> >
>> > On Jul 14, 2014, at 4:53 PM, Marc Schwartz <marc_schwartz at me.com>
>> wrote:
>> >
>> >> On Jul 14, 2014, at 4:13 PM, John Fox <jfox at mcmaster.ca> wrote:
>> >>
>> >>> Dear Simon and list members,
>> >>>
>> >>> As many of you are aware, when X11 isn't installed on Mac OS X,
>> loading the
>> >>> tcltk package produces an error, with a message that many users
>> find
>> >>> cryptic. There was yet another instance of this problem reported to
>> the list
>> >>> today.
>> >>>
>> >>> I'm interested in the issue because the Rcmdr package uses tcltk
>> and thus
>> >>> fails to load when X11 is absent. Rcmdr users tend to be
>> inexperienced and
>> >>> so, unless they find their way to the Rcmdr installation webpage,
>> where
>> >>> detailed installation instructions are provided, they tend to be
>> stymied by
>> >>> the problem.
>> >>>
>> >>> If I could, I'd intercept the problem by checking
>> capabilities()["X11"] in
>> >>> the Rcmdr .onLoad() or .onAttach() function, but because the Rcmdr
>> package
>> >>> imports the tcltk namespace, the error occurs before these startup
>> functions
>> >>> are executed -- a chicken-and-egg problem.
>> >>>
>> >>> It occurs to me that tcltk could fail more gracefully on Mac OS X
>> when X11
>> >>> is absent, perhaps popping up a webpage in a browser with
>> instructions and a
>> >>> link for installing XQuartz. I'd do this myself in the Rcmdr
>> package if I
>> >>> could. Or tcltk could check for the presence of X11 and not try to
>> start it
>> >>> if it's absent, reporting a warning rather than throwing an error.
>> >>>
>> >>> Alternatively, I'd be grateful if someone could suggest how I might
>> detect
>> >>> the problem in the Rcmdr package before loading fails. The only
>> thing that I
>> >>> could think of was writing a separate RcmdrInstall package that
>> bypasses
>> >>> tcltk, but that would be awkward and would only help users who
>> discovered
>> >>> that RcmdrInstall exists.
>> >>>
>> >>> Thanks,
>> >>> John
>> >>
>> >>
>> >> John,
>> >>
>> >> Is there someplace in your startup process where you could run code
>> along the lines of:
>> >>
>> >> if (grepl("apple", R.version$platform) &
>> length(list.files("/opt/X11/bin", pattern = "Xquartz")) == 0) {
>> >>     cat("X11 is required. Please visit http://xquartz.macosforge.org
>> to download and install Xquartz.")
>> >>     stop()
>> >> }
>> >>
>> >>
>> >> The above code will check to see if the user is running R on OS X
>> and also if the Xquartz binary is present in the default location.
>> >>
>> >> Not sure if this is helpful.
>> >
>> >
>> > A possible correction in the above code relative to detecting OS X:
>> >
>> > if ((Sys.info()["sysname"] == "Darwin") &
>> length(list.files("/opt/X11/bin", pattern = "Xquartz")) == 0) {
>> >     cat("X11 is required. Please visit http://xquartz.macosforge.org
>> to download and install Xquartz.")
>> >     stop()
>> > }
>> >
>> >
>> > I believe that Sys.info()["sysname"] == "Darwin" is preferred for
>> detecting the OS that R is running on versus the OS that it was built
>> upon according to the help files, if I read correctly. This could be
>> important if someone is building R from source versus installing
>> Simon's CRAN binary, I presume.
>> >
>> > Regards,
>> >
>> > Marc
>> >
>> > _______________________________________________
>> > R-SIG-Mac mailing list
>> > R-SIG-Mac at r-project.org
>> > https://stat.ethz.ch/mailman/listinfo/r-sig-mac
>