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

Marc Schwartz marc_schwartz at me.com
Tue Jul 15 14:05:43 CEST 2014 

John,

First, apologies for my narrow focus on the solutions that I proposed yesterday. I suffered from tunnel vision on the OS X issue and as Gabor has noted, it would not be sufficiently portable. There can be potential variations on where X11 is installed on OS X, depending upon the use of Xquartz, the original Apple distribution of X11 and presumably could further vary if one installs from source, is using Homebrew, Macports or similar, which are package management systems for OS X. Thus, as Gabor pointed out, capabilities("X11") is the most portable approach.

With respect to Linux, to the best of my knowledge, X11 (for some time X.org) is still a requirement for tk (but not tcl). In checking at least the current Fedora repos, X11 is still listed as a dependency for tk. So if one is using the common package management systems, X11 will be installed if not already, when installing tk, unless one overrides the defaults.

Also, at least for Fedora and perhaps other Linuxen, X11 is listed as a dependency for R itself, so if one is installing R on Fedora, X11 will be installed as well, if not present.

Thus, between the common Linux package management systems and that Linux users tend to be more technically saavy, you do not see many reports.

You likely already know this, but you could utilize a more generic approach to testing the platform by using:

  if (.Platform$OS.type == "unix")
    ...

which would cover Linuxen, Unixen and OS X and then run your X11 checks, secondarily perhaps testing for OS X, if you wish to give a more specific error message for OS X users and point them to XQuartz.

Regards,

Marc

 

On Jul 14, 2014, at 11:37 PM, John Fox <jfox at mcmaster.ca> wrote:

> Hi Gabor,
> 
> Thanks for the clarification.
> 
> I agree that it would be best to intercept the problem on Linux/Unix as well as on Mac OS X. Do you know that X11 is necessary for the tcltk package to work on Linux/Unix systems (or is there possibly a non-X11 Tcl/Tk there that's compatible with the tcltk package)?
> 
> As a practical matter, the problem occurs with some regularity on Mac OS X (I'm aware that the availability and default installation of X11 varies by version of the OS), but I've not seen a report of it on Linux, so my immediate concern was to solve the problem on Mac OS X.
> 
> Best,
> John
> 
> On Mon, 14 Jul 2014 21:37:54 -0400
> Gábor Csárdi <csardi.gabor at gmail.com> wrote:
>> 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
>>>

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