so is there a fix? Stef On Jun 4, 2009, at 11:07 PM, Hernan Wilkinson wrote:
yes, but not only that... I also create "complete objects" from its very first time. For example, instead of: Date new day:1; moth:1; year: 2009. I do: Date newDay: 1 moth: 1 year: 2009.
That way you will never have an invalid Date
2009/6/4 Steve Wirts <stevewirts@gmail.com> That's the Null Object Pattern!
http://en.wikipedia.org/wiki/Null_Object_pattern
2009/6/4 Hernan Wilkinson <hernan.wilkinson@gmail.com>
I was going to suggest exactly that. As a rule, I never use nil because if you do it you will have to check for it somewhere... nil is the root of most of the problems! if not, look at all the errors I fixed in the other mail, most of them are because nil is being used. So, instead of nil, another object has to be use, and like you said in this case an empty collection I think will work. I'm just changing that... I'll send the changes today (I hope).
Hernan.
On Thu, Jun 4, 2009 at 11:32 AM, Michael Rueger <m.rueger@acm.org> wrote: Sean Allen wrote:
Just as a bit more info. I used squeak for several months without ever seeing this error. I used pharo for 3 months without seeing this error. I've only gotten this error in the latest images with the latest vm and get it constantly. Not occassionally, I can get this to happen at least once every 120 seconds or so, sometimes more often. It would seem to be as an outsider, that something must have changed.
it definitely sounds like it. Would be good to investigate what might have changed in the call path that *sets* the variable to check why it is ending up being nil. Maybe it shouldn't be set or initialized to nil but to an empty collection in those cases?
Michael
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