Python descriptor example

descriptor.py

class LogCountDescriptor:

    def __init__(self, log_count=0):
        self.log_count = log_count

    def __get__(self, obj, type=None):
        print("log from {}".format(obj))
        self.log_count += 1
        return self.log_count

    def __set__(self, obj, value):
        raise AttributeError

class A:
    descriptor = LogCountDescriptor()

a = A()
print("access count: {}".format(a.descriptor))
print("access count: {}".format(a.descriptor))
print("access count: {}".format(a.descriptor))