[R] does R read commands from scripts instantanously or seuqently during processing

[Jannis]

Dear all,

thanks, Rolf and Jeff, for your replies. The command below runs under 
Suse Linux. I guess, hoewever, the phenomena I observed would heappen 
under other oprating systems as well. The reason why I asked was that R 
produced some error messages that did not really point me to the 
direction of the edited script file. These errors were usually something 
like:

Error: unexpected symbol in "cess finished."

The line in the script which caused this error is:

print(paste(as.character(Sys.time()), ': Process finished.', sep=''))

This line contains valid R code and would normally not produce an error. 
Some testing showed that the error above only happens when I edit the 
code of the script while the script is run. So R probably reads in a 
script submitted that way seuqently directly while executing the 
individual commands. No idea though what happens if i would start the 
script via source inside R itself.


Thanks again for your suggestions
Jannis


On 14.03.2013 22:47, Rolf Turner wrote:
> On 03/15/2013 05:13 AM, Jannis wrote:
>> Dear R community,
>>
>>
>> when I source a script into R via:
>>
>>
>> R --slave < scriptname.R
>>
>>
>> is the whole script file read at once during startup or is each
>> indivdual line of code read seqnetially during the execution (i.e.
>> directly before r processes the respective command)? In other words,
>> can I savely edit the  scriptname.R file even when an active R process
>> still runs the command above?
>
>
> Experiment.  Build a toy script with a loop that never terminates. Set
> it going.  Edit the script and change the code so that the loop terminates.
> See what happens.
>
> [It seems to me that nothing happens, so that you *can* "safely" edit
> the script while
> the process runs.  But further experimentation would be advisable.]
>
>      cheers,
>
>          Rolf Turner