OOP and Tkinter

[Ronny Mandal]

Hello.

I am stuck; provided is the code and error-msg:

file front_ui.py:

class Front(object):
_images = [] # Holds image refs to prevent GC
def __init__(self, root):


# Widget Initialization
self._listbox_1 = Tkinter.Listbox (root,
height = 0,
width = 0,
...
)






other file:

from Front_ui import Front

class CustomFront(Fro nt):


Front._listbox_ 1.insert( 0, 'foo' )

....
....
File "H:\My Documents\Komod o\Front.py", line 63, in CustomFront
Front._listbox_ 1.insert( 0, foo' )
AttributeError: type object 'Front' has no attribute '_listbox_1'


i.e., it cannot find the listbox! Strange, both files is in the same
folder. What is wrong here?


Thanks,

Ronny Mandal

[Diez B. Roggisch]

Re: OOP and Tkinter

Ronny Mandal schrieb:[color=blue]
> Hello.
>
> I am stuck; provided is the code and error-msg:
>
> file front_ui.py:
>
> class Front(object):
> _images = [] # Holds image refs to prevent GC
> def __init__(self, root):
>
>
> # Widget Initialization
> self._listbox_1 = Tkinter.Listbox (root,
> height = 0,
> width = 0,
> ...
> )
>
>
>
>
>
>
> other file:
>
> from Front_ui import Front
>
> class CustomFront(Fro nt):
>
>
> Front._listbox_ 1.insert( 0, 'foo' )
>
> ...
> ...
> File "H:\My Documents\Komod o\Front.py", line 63, in CustomFront
> Front._listbox_ 1.insert( 0, foo' )
> AttributeError: type object 'Front' has no attribute '_listbox_1'
>
>
> i.e., it cannot find the listbox! Strange, both files is in the same
> folder. What is wrong here?[/color]

That you refer to the type/class Front with expressions like Front.<...>
instead to an _instance_ of Front. You need to do things like this:

class CustomFront(Fro nt):
def __init__(self, root):
super(CustomFro nt, self).__init__( root) #now the super-classes
instance variables are there!
self._listbox_1 .insert( 0, 'foo' )




Diez

[Ronny Mandal]

Re: OOP and Tkinter


Thanks, but the problem was my undentation, after making one indent,
it worked as expected. :)


-Ronny M

[Kent Johnson]

Re: OOP and Tkinter

Ronny Mandal wrote:[color=blue]
> file front_ui.py:
>
> class Front(object):
> _images = [] # Holds image refs to prevent GC
> def __init__(self, root):
> # Widget Initialization
> self._listbox_1 = Tkinter.Listbox (root,
> height = 0,
> width = 0,
> ...
> )
>[/color]
[color=blue]
> other file:
>
> from Front_ui import Front
>
> class CustomFront(Fro nt):
> Front._listbox_ 1.insert( 0, 'foo' )
>
> ...
> ...
> File "H:\My Documents\Komod o\Front.py", line 63, in CustomFront
> Front._listbox_ 1.insert( 0, foo' )
> AttributeError: type object 'Front' has no attribute '_listbox_1'
>
>
> i.e., it cannot find the listbox! Strange, both files is in the same
> folder. What is wrong here?[/color]

_listbox_1 is an instance attribute, not a class attribute. You need to
refer to self._listbox_1 from a CustomFront method, or change _listbox_1
to a class attribute if that is what you really want.

Kent

[Diez B. Roggisch]

Re: OOP and Tkinter

Ronny Mandal schrieb:[color=blue]
> Thanks, but the problem was my undentation, after making one indent,
> it worked as expected. :)[/color]

I seriously doubt that. I guess you didn't show us the real code. But
there is no way that an instance variable can be accessed on type-level
in a derived class (or from anywhere, for that matter). So I presume you
have some misconceptions about pythons OO-model that will sooner or
later bite you - for example if you want to have several Front-objects.

Diez