R_Interactive {was '[Rd] stdout == 'Terminal' or 'File'}

[Prof Brian Ripley]

On Wed, 12 May 2004, Simon Urbanek wrote:

> while the topic is on, something remotely related although the same:
> 
> On May 12, 2004, at 10:04 AM, Prof Brian Ripley wrote:
> 
> > interactive() is as good a test as we have, and I think if a better 
> > test
> > is required in the interactive case, the user should be asked.
> 
> There may be a little problem in the current sources (talking unix for 
> now) - R sets the interactive flag like this:
> 
> system.c at 248:    R_Interactive = isatty(0);
> 
> Unfortunately right after this there comes:
> 
> if (!R_Interactive && SaveAction != SA_SAVE && SaveAction != SA_NOSAVE)
>     R_Suicide("you must specify `--save', `--no-save' or `--vanilla'");
> 
> Now speaking of embedded R - the above leaves (afaik) no way of telling 
> R to use interactive mode before this suicide attempt if stdout is no 
> tty (it doesn't have to if the embedding app provides its own 
> Read/WriteConsole etc.). Any thoughts on this? (btw: aqua uses a hack 
> to circumvent this... whenever aqua needs a hack it may be worth 
> thinking about something more general ;))

Not R per se, but the Unix front-end in Rf_initialize_R, which is a hack
from the terminal-like Unix front-end. As in the comment

    /* On Unix the console is a file; we just use stdio to write on it */

An embedding application can (and probably should) set argv when it calls
Rf_initEmbeddedR, or it can call its own version of Rf_initialize_R (which
is what happens under Windows).

BTW, this is in the process of being broken up (and aqua and gnome 
support moved to Rmain.c) so it is a good time for a better solution.
OTOH, it is not particularly good to break the API of which 
Rf_initialize_R is probably considered part.

I agree with your comment about aqua, but then those of us not using Raqua 
are often unaware of the hacks which have been used.

Brian

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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