I have a perplexing problem with Python 3 class variables. I wish to generate
an unique ID each time an instance of GameClass is created. There are two
versions of the __gen_id method with test run results for each listed below the
code.
Originally I used the version which is now commented out. When a new instance
was created it created an ID by appending the value of __instance_counter to
the class name, it then checked the contents of of __instatance_registrty to
see if this ID was already in use. If so it incremented the counter until it
found an unused ID. This version works exactly as I expected.
Later I decided to get rid of __instance_registry and rely solely on the
restricted access to __instance_counter and the fact that it is monotonically
increasing to generate IDs. I wrote the second, simpler version of __gen_id to
that end, but it doesn't work! No doubt I'm overlooking something very simple
here but I'm not seeing it.
Any help appreciated.
class GameObject:
# __instance_registry = {"":None}
__instance_counter = 0
def __init__(self, name):
self.__name = str(name)
self.__id = self.__gen_id()
# def __gen_id(self):
# ty = self.__class__.__name__
# id = ''
# while id in self.__instance_registry:
# id = '%s_%d' % (ty, self.__instance_counter)
# self.__instance_counter += 1
# self.__instance_registry[id] = self
# return id
def __gen_id(self):
ty = self.__class__.__name__
id = '%s_%d' % (ty, self.__instance_counter)
self.__instance_counter += 1
return id
def __str__(self):
return "name = '%s' id = '%s'" % (self.__name, self.__id)
go1 = GameObject("GO1")
go2 = GameObject("GO2")
go3 = GameObject("GO3")
print(go1)
print(go2)
print(go3)
# Results with original __gen_id method
# name = 'GO1' id = 'GameObject_0'
# name = 'GO2' id = 'GameObject_1'
# name = 'GO3' id = 'GameObject_2'
# Results with new simpler __gen_id method, __instance_counter not being
incremented
# name = 'GO1' id = 'GameObject_0'
# name = 'GO2' id = 'GameObject_0'
# name = 'GO3' id = 'GameObject_0'
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