Re: NEW FILE

[John Darrington]

On Fri, Jan 05, 2007 at 03:57:36PM -0800, Ben Pfaff wrote:
     We had a discussion about the necessity for NEW FILE recently,
     although for some reason I'm having trouble finding the thread.
     
     Anyhow, I found this text in the SPSS documentation for NEW FILE:
     
         When you build an active dataset with GET, DATA LIST, or
         other file-definition commands (such as ADD FILES or MATCH
         FILES), the active dataset is automatically replaced. It is
         not necessary to specify NEW FILE.

Interesting.  This seems to contradict some of my recent experiences
with spss.  I've have to look into it further.
     
     It implies elsewhere that NEW FILE is only necessary for use with
     INPUT PROGRAM.  So I doubt we should make changes in that area.

Regardless of this, there are some problems with the way NEW FILE
currently behaves in respect to the GUI.  Currently, it calls 
discard_variables in src/data/procedure.c  which in turn does:

  free_case_source (ds->proc_source);
  ds->proc_source = NULL;

Having proc_source as NULL, is something the GUI doesn't expect.
As previously discussed, there is always a source, albeit a possibly
empty one.  This is conflicting with the current GUI code, such that
if it runs a syntax whose last command is NEW FILE, then it finds
itself in a state where it refuses to parse any new commands.  There
are a number of possible solutions to this problem, but I haven't
decided which is the best one yet.

J'



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