From luke-tierney at uiowa.edu  Fri Sep  1 21:13:32 2017
From: luke-tierney at uiowa.edu (luke-tierney at uiowa.edu)
Date: Fri, 1 Sep 2017 14:13:32 -0500 (CDT)
Subject: [Rd] patch: automatically adjust width option when terminal is
 resized
In-Reply-To: <alpine.DEB.2.20.1709011403350.2718@luke-Latitude>
References: <20170828093331.39607d5b@delligoertz.fritz.box>
 <20170901102321.6921e48a@delligoertz.fritz.box>
 <alpine.DEB.2.20.1709010710340.2718@luke-Latitude>
 <20170901163836.26590c10@delligoertz.fritz.box>
 <alpine.DEB.2.20.1709011403350.2718@luke-Latitude>
Message-ID: <alpine.DEB.2.20.1709011412370.2718@luke-Latitude>

Accidentally dropped R-devel from this reply.

On Fri, 1 Sep 2017, luke-tierney at uiowa.edu wrote:

> On Fri, 1 Sep 2017, Ralf Goertz wrote:
>
>> Am Fri, 1 Sep 2017 07:20:58 -0500 (CDT)
>> schrieb luke-tierney at uiowa.edu:
>> 
>>> On Fri, 1 Sep 2017, Ralf Goertz wrote:
>>> 
>>>> Many good programs like vim adjust their internal width
>>>> representation automatically. Why shouldn't R do the same? It seems
>>>> quite easy, at least when readline is used:
>>>> 
>>>> 
>>>> --- R-3.4.1/src/unix/sys-std.c  2017-03-24 00:03:59.000000000 +0100
>>>> +++ R-3.4.1/src/unix/sys-std.patched.c  2017-08-28
>>>> 09:16:02.714204023 +0200 @@ -1005,6 +1005,9 @@
>>>>                // introduced in readline 4.0: only used for >= 6.3
>>>> #ifdef HAVE_RL_RESIZE_TERMINAL
>>>>                rl_resize_terminal();
>>>> +               int rl_height, rl_width;
>>>> +               rl_get_screen_size(&rl_height,&rl_width);
>>>> +               R_SetOptionWidth(rl_width);
>>>> #endif
>>>>             }
>>>> #endif
>>> 
>>> The 'width' option affects more than printing to the console; it also
>>> affects, for example, printing to a file via sink() or
>>> capture.output(). So doing this unconditionally would not be a good
>>> idea.  Making it available as an option for those who want it seems
>>> reasonable but still involves a lot more work than these three lines.
>>> It requires designing a protocol for enabling this feature, ideally in
>>> a way that can be made to work well on other interfaces (e.g. Windows,
>>> Mac, RStudio) as well, and it requires documenting all this in a
>>> sensible place. A more complete proposal might well be considered for
>>> adoption.
>> 
>> Hi Luke,
>> 
>> thanks for your explanation. I am not at all familiar with the R source
>> code nor am I a professional programmer. I found the place to do that
>> simply by grepping for the signal SIGWINCH. I was, however, aware that
>> it would need more than those three lines.
>> 
>> As to the other uses of the width option, wouldn't it make sense to have
>> a separate option for output redirection? Or even have file output
>> always use the same fixed width, say 80? After all, if the output is
>> saved to a file this file is probably meant to be viewed in another
>> context than the R terminal. And even if the width of file output is
>> affected I don't see any real harm since that is the way it is now. If
>> one really needs a specific width in such a case s/he can request it by
>> setting the option manually before outputting to a file.
>
> This could have been designed differently, but it wasn't and making
> chnages would cause code to break.
>
>> On the other
>> hand, the documentation says
>>
>> 	 ?width?: controls the maximum number of columns on a line used in
>> 		  ?
>> 		  ?Print.h? and can be changed by re-compiling R.)  Some R
>> 		  consoles automatically change the value when they are 
>> resized.
>
>
> Good point.
>
> The Windows R GUI does this if a preference option is set; I don't
> know what the default is from just a quick look at the sources.
>
> RStudio does this by default and there is no obvious way, to me at
> least, to turn it off, which is unfortunate given the
> sink/capture.output issues.
>
> I made changes to R-devel in r73180 to set width if the you set
> options(setWidthOnResize = TRUE). By default this option is not set
> and the width option is not changed. We'll see if it causes any
> problems.
>
> Best,
>
> luke
>
>
>> If *some* consoles already do automatically change the value when
>> resized why should an instance of R running in a pure terminal emulator
>> not be allowed to do so? In case there is a good reason, my idea for the
>> option is as follows. It stays as it is but it can also be negative
>> indicating that SIGWINCH will lead to an adjustment. That way nothing
>> changes for those users who do not bother at all. Also, this can easily
>> be documented, e.g. by appending the following line to the block quoted
>> above.
>>
>> 		  Others do so when 'width? is negative.
>> 
>> Interfaces which don't or can't use that feature or functions like print
>> merely have to call "abs(GetOptionWidth())" instead of
>> "GetOptionWidth()". Luckily, both "int GetOptionWidth()" and "int
>> attribute_hidden R_SetOptionWidth(int w)" are defined in terms of int,
>> so it is possible to send and receive negative values. I don't know
>> about the Windows or Mac interface. But I would imagine that they can
>> also be made to swallow negative width values rather easily.
>> 
>> Digging a little more I found that there had been the setwidth package
>> which basically did what I am asking for. Here
>> <https://groups.google.com/forum/#!topic/vim-r-plugin/SeQCNWxEPwk> the
>> author of that package (Jakson Aquino) explains that it stopped working
>> because R started to catch SIGWINCH itself. He continues: ?Perhaps this
>> feature could be implemented directly in R if someone requested it to
>> the R Core Team.? There really seems to be a need for this.
>> 
>> Ralf
>> 
>
>

-- 
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa                  Phone:             319-335-3386
Department of Statistics and        Fax:               319-335-3017
    Actuarial Science
241 Schaeffer Hall                  email:   luke-tierney at uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu


[Rd] patch: automatically adjust width option when terminal is resized
luke-tierney at uiowa.edu