R devel - Sep 2007 - Lack of final newline in write.dcf changes append usage

The change in r42731 eliminating the final blank line when writing DCF
files changes the way 'append' can be used in 'write.dcf' and I
was
wondering if this is intentional.  Basically, I want to write a data
frame to DCF format one row at a time, so I make use of repeated calls
to 'write.dcf(append = TRUE)'. However, in R 2.6.0RC the resulting DCF
file is not formatted properly because there are no blank lines
between the entries.

It seems the only way to use 'write.dcf(append = TRUE)' is to
explicitly write a blank line to the file before writing the entry.
Perhaps 'write.dcf' could be changed to write a blank line in the
beginning if append = TRUE?  I've attached a patch for this
possibility.

-roger
-- 
Roger D. Peng  |  http://www.biostat.jhsph.edu/~rpeng/

On Wed, 26 Sep 2007, Roger Peng wrote:
> The change in r42731 eliminating the final blank line when writing DCF
> files changes the way 'append' can be used in 'write.dcf'
and I was
> wondering if this is intentional.  Basically, I want to write a data
Yes, it is intentional.  That a blank line got written after a single 
record (only) was regarded as unintentional: blank lines are (I was told) 
record separators and not terminators.
> frame to DCF format one row at a time, so I make use of repeated calls
> to 'write.dcf(append = TRUE)'. However, in R 2.6.0RC the resulting
DCF
> file is not formatted properly because there are no blank lines
> between the entries.
tools::write_PACKAGES had that problem.  But surely it is better to keep a 
connection open and make repeated calls to write.dcf on it (as 
write_PACKAGES does).  I don't think writing record separators explicitly 
is much of a hardship.
> It seems the only way to use 'write.dcf(append = TRUE)' is to
> explicitly write a blank line to the file before writing the entry.
or after an entry.
> Perhaps 'write.dcf' could be changed to write a blank line in the
> beginning if append = TRUE?  I've attached a patch for this
> possibility.
Not in code freeze, and in any case it does not address what for me is the 
natural usage.

-- 
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)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595