(PR#2275) Re: Bug#168259: r-base-core: help.start() assumes netscape is installed

Note that this only a problem for pre-compiled versions of R used on
machines other than the one on which it was compiled. For those compiling
from source, the configure script selects a browser.  So almost all the
analysis is based on incorrect assumptions.

What you seem to want is run-time rather than compile-time automated
selection.

On Fri, 8 Nov 2002 edd@debian.org wrote:

Package: r-base-core
Version: 1.5.1-0woody1
Severity: minor

I don't have Netscape on my system. Trying to follow the sample

To best of my knowledge, this R feature dates from a time when
Netscape was essentially the only browser out there. It also had
a most useful feature: you could attach new request (resulting in
a new "frame" in X11 / window manager parlance) to a running Netscape
making startup for this request /much/ faster than starting a new
Netscape executable.

and netscape no longer allows multiple executables to run.

This feature lacks in other browsers which is why no one was able
to write a wrapper script around netscape, mozilla, galeon, konqueror,...
and pick whichever is found.

session in the R Intro fails with a less than helpful error message:

Then this should be fixed in the R Intro -- maybe a line could be added
suggesting that the   browser="foo"   options may be needed to switch
away from netscape?

Nope, what's in R-intro works everywhere R was compiled from source.
It's a Debian (etc) problem.

Type `demo()' for some demos, `help()' for on-line help, or
`help.start()' for a HTML browser interface to help.
Type `q()' to quit R.

help.start()

Making links in ~/.R ...
If netscape is already running, it is *not* restarted, and you must
    switch to its window.
Otherwise, be patient ...

sh: netscape: command not found

Could some heuristic be put in place to use whatever is installed
rather than blindly hope Netscape will be there? I thought I even saw

Again, that's not what happens.

This has been discussed on the R lists, but as I recall, no consensus
was reached for the reasons outlined above.

something about an /etc/alternatives mechanism for selecting a web
browser but this does not seem to exist (yet?)

Now you're switching from a generic R problem to a Debian specific
solution -- but yes I may be able to do that. However, what we would
really need is a wrapper like, say, sensible-browser akin to the
existing sensible-paper and sensible-editor.  Now, as I said above,
this will likely be difficult or impossible to do well, so nobody
did it.

Also, /etc/alternatives is designed to switch between variants of the
same program: emacs as a choice between emacs20 and emacs21, netscape
as one between static motif and other linkage variants, ... whereas
sensible-$FOO is a wrapper around different programs doing $FOO.

Failing that, perhaps the program could check for the existence of
Netscape before attempting to launch it, and display a suitable error
message if it is not installed (hopefully with instructions for how to
override).

Yes, but that is tough to do portably on Unix, Max, Win, ... where R
runs.

I was lucky enough to fairly quickly find an example of how to work
around this in Google; for the record, help.start(browser='mozilla')
worked for me, and apparently R will now remember to use Mozilla in
the future on my account.

Only for the running session. Set
  options(browser="mozilla")
in ~/.Rprofile to make it truly permanent.

Sorry if this is already fixed in testing/unstable.

No, I'd call it one of the "unfixable" ones.

Regards,  Dirk

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-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
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