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))