[GRASS-dev] python and GRASS_MESSAGE_FORMAT

[Daniel Calvelo]

Hi Jachym. This looks like a buffered vs. unbuffered stream problem.

Looking at lib/gis/percent.c, the output of (the G_percent calls of)
r.los should flush at every write so if you try to popen in unbuffered
mode, you should get what you need: try os.popen("your_cmd","r",0).

HTH, Daniel.

On 11/25/06, Jachym Cepicky <jachym.cepicky at centrum.cz> wrote:
> On Sat, Nov 25, 2006 at 06:56:14PM +0000, Glynn Clements wrote:
> > The documentation for the readlines() method says:
> >
> > readlines([sizehint])
> >
> >     Read until EOF using readline() and return a list containing the
> >     lines thus read. If the optional sizehint argument is present,
> >     instead of reading up to EOF, whole lines totalling approximately
> >     sizehint bytes (possibly after rounding up to an internal buffer
> >     size) are read. Objects implementing a file-like interface may
> >     choose to ignore sizehint if it cannot be implemented, or cannot
> >     be implemented efficiently.
> >
> > The "until EOF" means that it isn't going to return until the command
> > has completed.
> >
> > > Could somebody help me, how to do it? Could you point me to tcl code,
> > > which must solve this problem too?
> >
> > Looking at the Python docs, you probably want something like:
> >
> >       f = os.popen("r.los in=elevation.dem out=tmp 2>&1")
> >       try:
> >           for line in f:
> >               print line
> >       finally:
> >           f.close()
>
> thanks, Glynn,  but it does not seem to work - or it works the same way,
> like readlines() does.
>
> I have in the script:
>
> import os
> os.putenv("GRASS_MESSAGE_FORMAT","gui")
>
> f = os.popen("r.los --o in=elevation.dem out=tmp \
>         coordinate=603067.6875,4925297.0625 max_dist=10000 2>&1")
> try:
>     for line in f:
>         print line
> finally:
>     f.close()
>
> result is, lines are printed. but _after_ r.los finished it's
> calcualtions..
>
> do I understand something wrong?
>
> thanks
>
> jachym
>
> --
> Jachym Cepicky
> e-mail: jachym.cepicky at centrum.cz
> URL: http://les-ejk.cz
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-- 
-- Daniel Calvelo Aros