[R] Sweave & xtable [problem solved/workaround -> bug in xtable or textConnection?]

[Peter Dalgaard BSA]

Hedderik van Rijn <hedderik at cmu.edu> writes:

> Whereas this code snippet "silently" truncates the string, without
> warning:
> 
> con <- textConnection("output","w");
> sink(file=con);
> cat(paste(rep("123456789!",1000),collapse=""))
> sink()
> close(con)
> 
> I'm not sure which function (if any) to blame, but I definitely think
> that either cat or textConnection should have made sure that a warning
> "came through". As you mentioned, it is naive to assume an arbitrary
> line-length, but if the above code is not incorrect, my opinion is
> that it should warn users of incorrect output, or state it in the help
> pages.

The warning should be inside "output", shouldn't it? It actually isn't
there, so perhaps it is getting appended to the already overlong
string??

As I was trying to dig deeper, I ran into the following interesting
segfault on RH8.0:

> con <- textConnection("output","w");
> sink(file=con);
> cat(paste(rep("123456789!",1000),collapse=""))
> sink()
> close(con)
>
> output
[1]
"123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!123456789!!
123456789"
> cat(paste(rep("123456789!",1000),collapse=""))
Program received signal SIGSEGV, Segmentation fault.
0x4207a4cb in strlen () from /lib/i686/libc.so.6

(The cat(...) call being obtained with up-arrow command recall) 

Apparently this is not quite reproducible and might depend on stuff in
the workspace, but it looks suspicious. Will have a better look.
-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907