[EMAIL PROTECTED] wrote:
> Skip and Matimus,
>
> Thank you for your replies. Putting initialization in the constructor
> gets me what I want. But I'd like to understand this a bit more.
> Here's another script:
>
> class ScannerCommand:
> taskName = ''
> scanList = []
>
> def __init__(self, data):
> self.scanList = []
> self.scanList.append(data)
>
> if __name__ == '__main__':
> c1 = ScannerCommand("c1")
> c2 = ScannerCommand("c2")
> print "C1: "
> for data in c1.scanList:
> print " " + data
> print "C2: "
> for data in c2.scanList:
> print " " + data
>
> And here's the output, which is what I want:
> C1:
> c1
> C2:
> c2
>
> If scanList is a class variable shared between all instances of the
> class, then C1's list should have held "C2" when I printed it, since C2
> came along and changed scanList. But obviously, here it's not a class
> variable and the two instances have their own lists.
>
> If I don't initialize scanList in the constructor, then scanList is a
> class variable (in C++, it would be a static member of the class) that
> is shared among all instances of the class. If I do initialize
> scanList in the constructor, then scanList magically becomes an
> instance variable, with every instance of the ScannerCommand object
> having its own scanList list??? Is that really the way it works? I
> would have thought the C++ way, with some special syntax to distinguish
> a class variable from an instance variable, would be much easier to
> work with.
>
> Thanks again!
>
> Rob Richardson
> RAD-CON, Inc.
> Bay Village, OH
>
You shadowed the class attribute scanList by creating an instance
variable called self.scanList in the __init__ method:
self.scanList = []
Comment that line out and see what you get.
-Larry Bates
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