python exception triggers and custom exception class

python program is running, the program may throw an exception.

Throw: throw an exception using the raise command, you can use the base class for exceptions Exception, can also use custom exception class (inherit Exception class).

class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

# Define a class to raise Line errors
class LineError(Exception):   #继承自基类Exception
    def __init__(self,ErrorInfo):
        self.errorinfo=ErrorInfo
    def __str__(self):
        return self.errorinfo

class Line:
    def __init__(self, point1, point2):
        self.point1 = point1
        self.point2 = point2
 
        if point1.x==point2.x and point1.y==point2.y:
            raise LineError("Cannot create line")
  
line = Line(Point(1, 2), Point(1, 2))