[Newbies] Laser game tutorial again
benschroeder at acm.org
Sat Jul 21 13:01:54 UTC 2007
On Jul 21, 2007, at 8:25 AM, gruntfuttuck wrote:
> I'm getting three errors with the Test Runner. It would seem that a
> BlankCell object doesn't understand the message exitSides:
> Or do I actually. It looks like it should be:
> self exitSides := Dictionary new.
> self exitSides: Dictionary new.
> Is this another way to do assignment? Anyway it's not working and
> that's how
> the tutorial says to do it.
> I'm really curious to what the problem is. Can anyone enlighten me?
The exitSides: message looks like an accessor, a method for setting
the value of an instance variable. That method would be implemented
much like the assignment you give above:
exitSides := aDictionary
The preceding "self" isn't used when referring to the name of an
Accessors let other objects set the values of variables directly, and
are sometimes thought to be more helpful for possible later changes.
Sometimes they do things like alerting other objects of changes. When
there's no behavior above and beyond simple setting, from inside the
same object, their use is largely a matter of personal style.
I haven't read through the whole tutorial, but perhaps the exitSides:
method is defined elsewhere. In any case, I'd guess that you are
correct and it is trying to do an assignment, although it may also
need to do other things.
Hope this helps,
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