[ROOT] Root 3.02.07 and line length limitations

From: Heather Kelly (heather@lheapop.gsfc.nasa.gov)
Date: Mon Sep 16 2002 - 22:12:19 MEST


Hi,

I'm using ROOT 3.02.07 on Windows (and Linux).  I seem to be having a 
problem with the length of a cut applied during a Draw command.
The problem seems linked to the line length and the length of the 
expression passed to TCut.  If I split my TCut expression into 2 parts, and 
defined 2 separate TCuts, I seem to retrieve the proper number of events.
Originally, I defined my TCuts within an unnamed macro - when I attempted 
to do the same directly at the command line - I did receive a useful 
warning message:
!!! User command too long !!!
(Is there some way to receive such warning messages, even if one uses an 
unnamed macro?  That would have been very useful to track down the problem)

Searching the ROOT/cint source, I see a constant:
#define G__ONELINE      256  /* Length of subexpression,parameter,argument */

So, expressions passed to a TCut must be <= 256 characters - correct?  At 
least within the interpreter.
The full cut did exceed 350 characters.

Now, I also found the same odd behavior (where the number of events 
adhering to a cut depends upon whether or not I split the cut into 2 
pieces) with a version I compiled into a separate application.  Is there 
some expression length limit overall - that is not just dependent upon cint?

Thanks,
Heather



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