The context management protocol of Python object-oriented programming

With open (' path ', ' R ', encoding= ' utf-8 ') as F:

code block

This is called the on-line management protocol, the WITH statement, in order for an object to be compatible with the WITH statement, the __enter__ and __exit__ methods must be declared in the class of the object.

Context Management Protocol:

Class Open:

def __init__ (self,name):

Self.name=name

def __enter__ (self):

Print (' A With statement appears, the object's __enter__ is triggered, the return value is assigned to the variable ' as declared ')

#return Self

def __exit__ (SELF,EXC_TYPE,EXC_VAL,EXC_TB):

Print (' important code block after execution, after I'm done! ‘)

Exc_type: Exception type

, Exc_val: Exception value

, EXC_TB: Traceability type

　　　　　

The context management protocol of Python object-oriented programming