[Tutor] generating independent random numbers
Steven D'Aprano
steve at pearwood.info
Tue Sep 28 02:27:07 CEST 2010
On Tue, 28 Sep 2010 08:55:36 am Carter Danforth wrote:
> class Date:
> c = random.randint(16,30)
> y = random.randint(0,99)
> month = random.randint(1,12)
Here's your problem: you are creating a class where all the attributes
(called "members" in some other languages) belong to the class and are
shared by all instances.
Python classes are themselves objects, and the code inside the class
body gets executed *once*, when the class is created. So in this case,
the Date class chooses a single random month, *once*, and all instances
share this attribute Date.month.
To get the behaviour you are after, you need to use instance attributes,
which means referring to self. The usual place to do this is in the
__init__ method, which is called when the instance is being
initialised:
class Date:
def __init__(self):
self.month = random.randint(1,12)
# etc.
By the way, why do you calculate a century and year separately, then add
c+y to get the year? It would be easier to just say:
year = random.randint(1600, 3099)
--
Steven D'Aprano
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