python中with用法讲解

class Foo():
  def __enter__(self):
    print("enter called")
  def __exit__(self, exc_type, exc_val, exc_tb):
    print("exit called")
    print("exc_type :%s"%exc_type)
    print("exc_val :%s"%exc_val)
    print("exc_tb :%s"%exc_tb)


with Foo() as foo:
  print("hello python")
  a = 1/0
  print("hello end")

enter called
Traceback (most recent call last):
hello python
exit called
exc_type :<class 'ZeroDivisionError'>
exc_val :division by zero
 File "F:/workspaces/python_workspaces/flask_study/with.py", line 25, in <module>
  a = 1/0
exc_tb :<traceback object at 0x0000023C4EDBB9C8>
ZeroDivisionError: division by zero

Process finished with exit code 1

print("hello python")
a = 1/0
print("hello end")