[nimh-dev] bugs in mhlib

[Joel Uckelman <uckelman@xxxxxxxxx>]

Rather than drink myself into a stupor after botching my abstract algebra 
final, I decided to do something constructive and hack on nimh tonight. 
I've been trying to finish Folder.parsesequence() and I've run into 
something which I think is a bug in mhlib. If you scan for a sequence which 
doesn't exist, an Error is thrown, but there's no error message 
accompanying it.

Here's the relevant bit of code from Folder.parsesequence():

try:
  n = self._parseindex(seq, all)
except Error, msg:
  seqs = self.getsequences()
  if not seq in seqs:
    if not msg:
      msg = "bad message list %s" % seq
    raise Error, msg
  return seqs[seq]

If you do a 'scan.py foo', self._parseindex() will do this:

raise Error, None

Following along in the code above, it catches the Error and checks whether 
foo is a user-defined sequence. Now, here's where things go bad. I think 
what was intended is that if foo isn't a sequence, then we'll have no error 
message, so one needs to be set. The problem is that msg is the Error 
object, not the error string, and the error object never evaluates to 
false, so the proper message never gets set.

Do either of you know whether the semantics for exception objects has 
changed recently, like maybe they evaluated to their string contents or 
something? Otherwise, I don't see how this could ever have worked 
properly...

-- 
J.


_______________________________________________
nimh-dev mailing list
nimh-dev@xxxxxxxxxxx
http://lists.ellipsis.cx/mailman/listinfo/nimh-dev