问题
im new to python and am struggling to understand why i keep getting "AttributeError: worker instance has no attribute 'workerNo'" when i call main().
beltLength = 5
class worker:
def __init__(self, wId):
workerNo = wId
def main():
production_Line = productionLine()
workers = []
for index in xrange(0, beltLength*2):
workers.append(worker(index))
print workers[index].workerNo
My thinking is that it should append 10 new worker instances with a workerNo attribute which is equal to index in a list. Thanks
回答1:
The issue here is that you are using a local variable when you should be using an instance variable.
Calling a function or method creates a new namespace, which exists only for the duration of the call. In order for the value of workerNo (worker_no would be better according to PEP 8, the standard for Python code) to persist beyond the __init__() method call it has to be stored in a namespace that doesn't evaporate.
Each instance has such a namespace (which is created when its class is instantiated), and the self (first) argument to every method call gives access to that namespace. So in your __init__() method you should write
self.workerNo = wId
and then you can access it from the other methods (since they also receive a self argument referring to the same namespace. External references to the instance can also access the instance attributes.
回答2:
You need the self before your workerNo.
class worker:
def __init__(self, wId):
self.workerNo = wId
You should consider reading this excellent answer as to why.
来源：https://stackoverflow.com/questions/22158202/instance-has-no-attribute