with上下文的實行是通過Python內(nèi)置的魔法函數(shù)實現(xiàn)的

class Example:
    
    def __enter__(self):
        print("enter")
        return self
        
    def __exit__(self,exc_type,exc_val,exc_tb):
        #釋放資源
        print("exit")
        
    def do_something(self):
        print("doing something")

with Example() as ex:
    ex.do_something()

enter
doing something
exit