Recursion problem

[Raymond Hettinger]

Hello Dennis,

I suspect that you want a separate data array for each instance of Compound.
Right now, both c and d share the same list.  Separate them the way you did
with Simple.  This should run nicely:

class Simple:
    def __init__(self,x):
        self.data = x
    def getData(self):
        return self.data

class Compound:
    def __init__(self):
        self.data = []
    def getData(self):
        y = ""
        for i in self.data:
            y += i.getData()
        return y

def test():
    a = Simple("hello")
    b = Simple("goodbye")
    c = Compound()
    c.data.append(a)
    c.data.append(b)
    print c.getData()
    d = Compound()
    d.data.append(c)
    print d.getData()


Raymond Hettinger


"Dennis Peterson" <denpeterson at yahoo.com> wrote in message
news:ac7d2u02vgg at enews2.newsguy.com...
> I'm trying to implement a basic Composite pattern. In the following code,
I
> expect c.getData() and d.getData() to both return "hellogoodbye". Instead,
> on d.getData() I get stacktrace printing "y += i.getData()" repeatedly
until
> recursion depth exceeded. Why?
>
> I'm new to Python, running latest Windows version just downloaded.
>
> class Simple:
>     def __init__(self,x):
>         self.data = x
>     def getData(self):
>         return self.data
>
> class Compound:
>     data = []
>     def getData(self):
>         y = ""
>         for i in self.data:
>             y += i.getData()
>         return y
>
> def test():
>     a = Simple("hello")
>     b = Simple("goodbye")
>     c = Compound()
>     c.data.append(a)
>     c.data.append(b)
>     print c.getData()
>     d = Compound()
>     d.data.append(c)
>     print d.getData()
>
>