[Tutor] question about OOP (or just grammer thing) ?

[Lloyd Kvam]

def myfunc( **kwargs)
is the python syntax (grammar) for collecting all of the key word arguments.

myfunc(len=1,width=3,units='cm') specifies three keyword (labeled) arguments.

The actual function will receive those arguments as a dictionary with the
name kwargs.  The ** signals python to collect the keyword arguments into a
dictionary.

I can't say much about the Tkinter processing specifics, but you can see that this
provides a convenient mechanism for packaging long "lists" of arguments.

Geonjae Lee wrote:

> Hi I'm a python newbie.
> I'm studying Tkinter.
> And All I know about programming language was C.
> That means I'm also not used to the OOP concept.
> 
> ==================================================================
> 
> from Tkinter import *
> 
> class HelloButton(Button):
>     def __init__(self, parent=None, **config):
>         Button.__init__(self, parent, config)
>         self.pack()
>         self.config(command=self.callback)
> 
>     def callback(self):
>         print 'Goodbye world...'
>         self.quit()
> 
> if __name__ == '__main__':
>     HelloButton(text='Hello subclass world').mainloop()
> 
> ===================================================================
> 
> I'm reading Programming Python 2nd edition published by O'reilly and
> also struggle to understand concept of class. 
> 
> 1. In the above example, variable named 'config' is used in 3 places. 
> Are they all same or different?
> 
> 2. I guess they're not all same. 
>     def __init__(self, parent=None, **config):
>         Button.__init__(self, parent, config)
> 
> I guess variable config in above 2 lines are same one.
> If then, why '**config' is used in __init__ method ? 
> And I tried to use just 'config' instead of '**config', but that caused
> a error.
> 
> 
> Thanks in advance.
> ThomasLee (KJ Lee)
> 
> 
> 
> 
> 
> 
> 
> 
> _______________________________________________
> Tutor maillist  -  Tutor@python.org
> http://mail.python.org/mailman/listinfo/tutor
> 
> 


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Lloyd Kvam
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