string.split returns empty when unaccessed

[Jonathan Pennington]

I'm having a problem spliting a string that is not accessed in some
way before the split. I am using the pygarmin module (modified) and
wxPython to build a GUI mapping program on a FreeBSD system with the
Python port v2.0. The code that retrieves the list is very long and
spans 3 modules, so it is not included here. I'm hoping that this is a
known problem or at least understandable from this limited info, and
the code is not needed, but I can provide it offlist if necessary.

Given a string foo returned from a class instance, string.split(foo,
'sep') returns [''] instead of a list of string items. However, if I
print foo, then try string.split(foo, 'sep') I *will* get a good
list. Copying as foo = foo[:] before splitting causes the same
behavior.  

What happens is:

> gps = garmin(UnixSerialLink('/dev/cuaa0'))
> w = gps.getWaypoints()
> t = string.split(w, '|R|')
> print t
['']
> w = gps.getWaypoints()
> w = w[:]
> t = string.split(w,'|R|')
> print t
['']
> w = gps.getWaypoints()
> print 'w'
[... waypoints ...]
> t = string.split(w,'|R|')
> print t
['name:V:stuff','cmnt:V:more stuff','lat:V:number','lon:V:number'...]

I can't figure out why that would happen, has anyone seen this before?
I can't seem to find a reference to the behavior anywhere. I'm still
new to the Python object model, but referencing it before splitting
doesn't seem like it should change it at all.

I've changed quite a bit in PyGarmin and there's a lot of code
accessed, but the instance that returns the string is below. Thanks. 

--------------class follows---------------------

import UserString
class D104(Waypoint, UserString.UserString):
   parts = Waypoint.parts + ("dst", "smbl", "dspl")
   fmt = "<6s l l L 40s f h b"

   def __init__(self, ident="", slat=0L, slon=0L, cmnt="", dst=0L, smbl=0L, dspl=0L):
      self.ident = ident         # text identidier (upper case)
      self.slat = slat           # lat & long in semicircle terms
      self.slon = slon       
      self.cmnt = cmnt           # comment (must be upper case)
      self.unused = 0L
      self.dst = dst                  # proximity distance (m)
      self.smbl = smbl                   # symbol_type id
      self.dspl = dspl                   # D104 display option
      self.data = ""
            
   def __repr__(self):
      self.data = "name:V:%s|R|cmnt:V:%s|R|lat:V:%i|R|lon:V:%i|R|dst:V:%i|R|smbl:V:%i|R|dspl:V:%i" % \
             (self.ident, self.cmnt, self.slat, self.slon, self.dst, \
              self.smbl, self.dspl)
      return self.data

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