>>>>> "BDR" == Prof Brian Ripley <[EMAIL PROTECTED]>
>>>>> on Wed, 12 May 2004 09:04:05 +0100 (BST) writes:
BDR> First, on an R console, stdout() is normally neither a
BDR> `normal file' nor a `user terminal'.
strictly yes, but that was not the point.
I have been looking for an API we could use to find some useful
information, and the original topic was about Sweave where
there will a file {when in normal use}.
BDR> Let alone under an embedded R ... or use under ESS (where for you,
BDR> Martin, it is neither).
well, I knew this, but ESS (i.e. 'comint' in Emacs) is quite
good at behaving like a user terminal in many situations;
e.g the 'scp' (secure copy) "visual counter" works very nicely
in Emacs' *shell* buffers.
BDR> On vanilla R under Unix-alikes (and Rterm but not
BDR> otherwise) what stdout is is a function of the C
BDR> runtime system. It's up to the C system if it tells
BDR> you what stdout has been redirected to, and if it can
BDR> tell you whether it is a terminal, or a pty (as used
BDR> under some versions of Emacs) or a file or a socket
BDR> .... The information is at best unreliable.
ok; that (the unreliabilty of the info you get) is bad news.
Thank you for the clarification.
BDR> interactive() is as good a test as we have, and I think
BDR> if a better test is required in the interactive case,
BDR> the user should be asked.
we can live with that, but I think other softwares at least try
to do better here.
------------------
A completely different way, less nice in several ways, but maybe
more reliable: There's a workaround we could start using here:
ESS has been setting
options(STERM= ...)
for a while now to indicate to the S process which kind of
"terminal" (excuse the term) it is running in.
The ESS manual currently contains
>> Is the Statistical Process running under ESS?
>> =============================================
>>
>> For the S languages (S, S-Plus, R) ESS sets an option in the current
>> process that programs in the language can check to determine the
>> environment in which they are currently running.
>>
>> ESS sets `options(STERM="iESS")' for S language processes running in
>> an inferior `iESS[S]' or `iESS[R]' buffer.
>>
>> ESS sets `options(STERM="ddeESS")' for independent S-Plus for Windows
>> processes running in the GUI and communicating with ESS via the DDE
>> (Microsoft Dynamic Data Exchange) protocol through a `ddeESS[S]' buffer.
>>
>> Other values of `options()$STERM' that we recommend are:
>>
>> * `length': Fixed length xterm or telnet window.
>>
>> * `scrollable': Unlimited length xterm or telnet window.
>>
>> * `server': S-Plus Stat Server.
>>
>> * `BATCH': BATCH.
>>
>> * `Rgui': R GUI.
>>
>> * `Commands': S-Plus GUI without DDE interface to ESS.
>>
>> Additional values may be recommended in the future as new interaction
>> protocols are created. Unlike the values `iESS' and `ddeESS', ESS
>> can't set these other values since the S language program is not under
>> the control of ESS.
and maybe we (R developers) should also consider setting some of
these (e.g. STERM = "Rgui" in that case) -- at least when the
info is available (and somewhat reliable) and even better think
about what else (better) could be done, working with options()
settings as a workaround for this problem.
Also (for the original topic), maybe Sweave() could set
options(STERM = 'Sweave') if options(STERM = 'BATCH) is not good
enough. Then, code like Martin Schlather's use
switch(getOption("STERM"),
"BATCH" = { .........},
....
)
BDR> On Wed, 12 May 2004, Martin Maechler wrote:
>> >>>>> "MartinS" == Martin Schlather <[EMAIL PROTECTED]>
>> >>>>> on Wed, 12 May 2004 09:15:17 +0100 writes:
>>
MartinS> Dear Ben,
>>
MartinS> I do not know how to solve the general problem that
MartinS> backspaces cause within Sweave, but which are
MartinS> needed to implement running counters.
>> aha! now I understand more what you are talking about.
>>
>> This is a more interesting problem, in general: It's not
>> quite a matter of if(interactive()) that Ben tried, but
>> really you want to find out if the stdout() connection
>> you are using is a normal file (where you don't need or
>> want a running counter) or a user terminal where Martin
>> Schlather applied the 1^H2^H... ('1' Backspace '2'
>> Backspace ..) trick.
>>
>> Any ideas what can be done here, using our current
>> connection tools -- or is there the need for something
>> new? Interesting topic!
>>
>> Martin Mächler
>>
>> PS. I know that strictly speaking the subject question is
>> non-sense, since, at least on Unix-alikes, a console is a
>> special file as well, and stdout is always a file.
BDR> -- Brian D. Ripley, [EMAIL PROTECTED] Professor of
BDR> Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
BDR> University of Oxford, Tel: +44 1865 272861 (self) 1
BDR> South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG,
BDR> UK Fax: +44 1865 272595
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