simple question

[Joonas Paalasmaa]

Bignose3 wrote:
> 
> I am a student starting to learn python coming from a C++ background.
> I am writing a simple simulation program were I am trying to assign
> each "swimmer" an ID.  Unfortunatley the way I would do it in C++
> doesnt work for python.  Can someone guide me in the right direction.
> 
> Here is the code that doesnt work, see what I am trying to do:
> 
> nextID= 0
> class swimmer:
>     def __init__(self, xpos, ypos):
>         self.ID = nextID
>         nextID= nextID + 1
>         self.xpos= xpos
>         self.ypos= ypos
>     def xcord(self):
>         print self.xpos
>     def ycord(self):
>         return self.ypos
>     def swimmerID(self):
>         return self.ID
> 
> An explanation would be great to.  Not a complex program but you have
> to start somewhere:)

Add the global statement to __init__ achieve the result simply.

class swimmer:
    def __init__(self, xpos, ypos):
	global nextID
        self.ID = nextID
        nextID= nextID + 1
        self.xpos= xpos
        self.ypos= ypos
    def xcord(self):
        print self.xpos
    def ycord(self):
        return self.ypos
    def swimmerID(self):
        return self.ID

>>> swimmer(1,2).swimmerID()
0
>>> swimmer(1,2).swimmerID()
1
>>> swimmer(1,2).swimmerID()
2
>>> swimmer(1,2).swimmerID()
3