RE: Class, object question.

[Ian Sparks]

Use the *args positional-argument to catch all the positional arguments in the constructor then test them to see what you have and call a kind of sub-init based on that : class Point:     def __init__(self,x,y,z):         self.x = x         self.y = y         self.z = z   class Vector:     def __init__(self,*args):         if len(args) == 3:             self.setFromValues(args)         elif len(args) == 2:             if isinstance(args[0],Point):                 self.setFromPoints(args)         else:             raise "Incorrect constructor"                          print self.i,self.j,self.k       def setFromValues(self,args):         self.i,self.j,self.k = args       def setFromPoints(self,args):         self.i = args[1].x - args[0].x         self.j = args[1].y - args[0].y         self.k = args[1].z - args[0].z   v = Vector(1,2,3)   p1 = Point(2,2,2) p2 = Point(4,4,4)   v2 = Vector(p1,p2)    Hope this helps.        -----Original Message----- From: Jeffrey Maitland [mailto:[EMAIL PROTECTED] Sent: Tuesday, April 05, 2005 10:04 AM To: python-list@python.org Subject: Class, object question. Hello folks,   The question I am having is something like this.   # ignore the precursing ….  I am using them for easy message formatting   from point import *   Class vector(point): ..........def __init___(self, point1, point2): ……………..self.i = point2.get_x() - point1.get_x() ……………..self.j = point2.get_y() - point1.get_y() ……………..self.k =  point2.get_z() - point1.get_z()   # methods of vector. Defined here.   What I am wondering is if I have a 2nd init  or something similar to create a vector. Such as what follows and if I can how do I go about implementing it?   Class vector(point): ..........def __init___(self, point1, point2): ……………..self.i = point2.get_x() - point1.get_x() ……………..self.j = point2.get_y() - point1.get_y() ……………..self.k =  point2.get_z() - point1.get_z() . ..........def __init___(self, i, j, k): ……………..self.i = i ……………..self.j = j ……………..self.k = k   That way I can define a vector either using 2 points or if I have the vector data itself?   Thanks in advance   Jeff

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