[Tutor] What does parent=0 mean?

[Danny Yoo]

On Tue, 24 Aug 2004, Klas Marteleur wrote:

> I am going thru theGUI programing chapter in Alans latest web tutorial. And
> found this example:

> -----------------------------------------
> from Tkinter import *
>
> class ClearApp:
>    def __init__(self, parent=0):
>       self.mainWindow = Frame(parent)
>       # Create the entry widget

[code cut]


> What does parent=0 mean?


Hi Klas,

This is an example of a default parameter.  Python allows us to declare
default values for the parameters of a function.  For example:

###
>>> def sayHello(name="Klas"):
...     print "hello", name
...
>>> sayHello()
hello Klas
>>> sayHello('dyoo')
hello dyoo
###


So if we don't pass a parameter off, Python uses the default value. The
Python Tutorial talks about this in section 4.7.1. "Default Argument
Values":

    http://www.python.org/doc/tut/node6.html#SECTION006710000000000000000




Hope this helps!