Mysterious "Attribute Errors" when GUI Programming

**Robert Kern** · Jul 18 '05, 10:22 PM

Re: Mysterious "Attrib ute Errors" when GUI Programming

Coral Snake wrote:[color=blue]
> I am having problems with programming even simple "Hello World"
> programs from books and tutorials that use Python GUI libraries. Such
> Programs cause python to throw "Attribute Errors" even when the
> "attributes " being asked for by the errors exist in the source code.
> This has happened to me in both the standard python GUI Library Tkinter
> and in pyGTK here are the codes for the "Hello World Programs involved
> and their corosponding "Attribute Errors":[/color]

It might help us if you cited where these "Hello World" programs are
coming from.

[snip]
[color=blue]
> def __init__(self):
> self.window = gtk.Window(gtk. WINDOW_TOPLEVEL )
> self.window.con nect("delete_ev ent", self.delete_eve nt)
> self.window.con nect("destroy", self.destroy)
> self.window.set _border_width(1 0)
> self.button = gtk.Button("Hel lo, World!")
> self.button.con nect("clicked", self.hello, None)
> self.button.con nect_object("cl icked",
> gtk.Widget.dest roy, self.window)
> self.window.add (self.button)
> self.button.sho w()
> self.window.sho w()
>
> def main(self):
> gtk.main()[/color]

Are you sure about the indentation here? Because I'm willing to bet
that's your problem in this example. I can't help with the Tkinter one,
though.
[color=blue]
> if __name__ == "__main__":
> hello = HelloWorld()
> hello.main()
>
> ------------------------------------------------------------
>
> AttributeError: HelloWorld instance has no attribute 'main'
>
> ------------------------------------------------------------
> As you can see if you look at this code the "attributes "
> being asked for by both programs exist in the source code but python
> insists that they DON'T.[/color]

No, searching the source code for Tkinter shows no "Toplevel.p ack"
method (or in any of its base classes). Where is this program coming
from? As for your GTK example, you have incorrect indentation.
[color=blue]
> What I want to know is what kind of bugs
> either in my source code or in Python itself leads it to to throw these
> "Attribute Errors" when the "attribute" being asked for by the error
> exists in the source code.[/color]

--
Robert Kern
rkern@ucsd.edu

"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter

**Steve Holden** · Jul 18 '05, 10:22 PM

Re: Mysterious "Attrib ute Errors" when GUI Programming

Coral Snake wrote:[color=blue]
> I am having problems with programming even simple "Hello World"
> programs from books and tutorials that use Python GUI libraries. Such
> Programs cause python to throw "Attribute Errors" even when the
> "attributes " being asked for by the errors exist in the source code.
> This has happened to me in both the standard python GUI Library Tkinter
> and in pyGTK here are the codes for the "Hello World Programs involved
> and their corosponding "Attribute Errors":
>
> ----------------------------------------------------------
> Tkinter:
>
> from Tkinter import *
> root = Tk()
> win = Toplevel(root)
> win.pack()
> Label(win, text= "Hello, Python World").pack(si de=TOP)
> Button(win, text= "Close", command=win.qui t).pack(side=RI GHT)
> win.mainloop()
> ---------------------------------------------------------
>
> AttributeError: Toplevel instance has no attribute 'pack'
>
> ---------------------------------------------------------
> pyGTK
>
> import pygtk
> pygtk.require(' 2.0')
> import gtk
>
> class HelloWorld:
> def hello(self, widget, data=None):
> print "Hello World"
>
> def delete_event(se lf, widget, event, data= None):
> print "delete event occured"
> return gtk.FALSE
>
> def destroy(self, widget, data = None):
> gtk.main_quit()
>
> def __init__(self):
> self.window = gtk.Window(gtk. WINDOW_TOPLEVEL )
> self.window.con nect("delete_ev ent", self.delete_eve nt)
> self.window.con nect("destroy", self.destroy)
> self.window.set _border_width(1 0)
> self.button = gtk.Button("Hel lo, World!")
> self.button.con nect("clicked", self.hello, None)
> self.button.con nect_object("cl icked",
> gtk.Widget.dest roy, self.window)
> self.window.add (self.button)
> self.button.sho w()
> self.window.sho w()
>
> def main(self):
> gtk.main()
>
> if __name__ == "__main__":
> hello = HelloWorld()
> hello.main()
>
> ------------------------------------------------------------
>
> AttributeError: HelloWorld instance has no attribute 'main'
>
> ------------------------------------------------------------
> As you can see if you look at this code the "attributes "
> being asked for by both programs exist in the source code but python
> insists that they DON'T. What I want to know is what kind of bugs
> either in my source code or in Python itself leads it to to throw these
> "Attribute Errors" when the "attribute" being asked for by the error
> exists in the source code.
>[/color]

There's absolutely no point trying do divine how to write Tkinter-based
programs by reading the source, though it's a brave approach. But ...
[color=blue][color=green][color=darkred]
>>> from Tkinter import *
>>> root = Tk()
>>> win = Toplevel(root)
>>> "pack" in dir(win)[/color][/color][/color]
False[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

tells you, absolutely beyond a shadow of a doubt, that Toplevel windows
don't have a "pack" method.

Take a look at a few of the working examples of Tkinter programs, that
should tell you what you are doing wrong.

regards
Steve

**klappnase** · Jul 18 '05, 10:23 PM

Re: Mysterious "Attrib ute Errors" when GUI Programming

"Coral Snake" <coralsnake2@ya hoo.com> wrote in message news:<111026350 1.198651.111150 @f14g2000cwb.go oglegroups.com> ...
[color=blue]
> ----------------------------------------------------------
> Tkinter:
>
> from Tkinter import *
> root = Tk()[/color]

This creates the application's main window. The Tk() command is not
some kind of initialization routine, but actually returns a ready to
use toplevel widget.
[color=blue]
> win = Toplevel(root)[/color]

This creates a child window with the parent "root";
[color=blue]
> win.pack()[/color]

here you try to put the child window into the main window; this cannot
work,
because a Tk() or Toplevel() window cannot contain other Toplevel()
instances.
Toplevel() is used for things like dialogs. If you need a separate
container
widget inside "root" use Frame() instead.
[color=blue]
> Label(win, text= "Hello, Python World").pack(si de=TOP)
> Button(win, text= "Close", command=win.qui t).pack(side=RI GHT)
> win.mainloop()
> ---------------------------------------------------------
>
> AttributeError: Toplevel instance has no attribute 'pack'
>
> ---------------------------------------------------------[/color]

The correct usage of what you tried looks like this:

from Tkinter import *
root = Tk()
Label(win, text= "Hello, Python World").pack(si de=TOP)
Button(win, text= "Close", command=win.qui t).pack(side=RI GHT)
root.mainloop()

I hope this helps

Michael

**Coral Snake** · Jul 18 '05, 10:24 PM

Re: Mysterious "Attrib ute Errors" when GUI Programming

klappnase wrote:[color=blue]
> "Coral Snake" <coralsnake2@ya hoo.com> wrote in message[/color]
news:<111026350 1.198651.111150 @f14g2000cwb.go oglegroups.com> ...[color=blue]
>[color=green]
> > ----------------------------------------------------------
> > Tkinter:
> >
> > from Tkinter import *
> > root = Tk()[/color]
>
> This creates the application's main window. The Tk() command is not
> some kind of initialization routine, but actually returns a ready to
> use toplevel widget.
>[color=green]
> > win = Toplevel(root)[/color]
>
> This creates a child window with the parent "root";
>[color=green]
> > win.pack()[/color]
>
> here you try to put the child window into the main window; this[/color]
cannot[color=blue]
> work,
> because a Tk() or Toplevel() window cannot contain other Toplevel()
> instances.
> Toplevel() is used for things like dialogs. If you need a separate
> container
> widget inside "root" use Frame() instead.
>[color=green]
> > Label(win, text= "Hello, Python World").pack(si de=TOP)
> > Button(win, text= "Close", command=win.qui t).pack(side=RI GHT)
> > win.mainloop()
> > ---------------------------------------------------------
> >
> > AttributeError: Toplevel instance has no attribute 'pack'
> >
> > ---------------------------------------------------------[/color]
>
> The correct usage of what you tried looks like this:
>
> from Tkinter import *
> root = Tk()
> Label(win, text= "Hello, Python World").pack(si de=TOP)
> Button(win, text= "Close", command=win.qui t).pack(side=RI GHT)
> root.mainloop()
>
> I hope this helps
>
> Michael[/color]

Thank you all. It appears that I was right in my original opinion of
source code from the Python Developer's Handbook by Andre Lessa and the
PyGTK Tutorial. That is where these source codes came from.

The code in Question came from the Chapter Getting Started in the PyGTK
Tutorial and from Chapter 15, page 579 in the Python Developer's
Handbook.

**Robert Kern** · Jul 18 '05, 10:24 PM

Re: Mysterious "Attrib ute Errors" when GUI Programming

Coral Snake wrote:
[color=blue]
> Thank you all. It appears that I was right in my original opinion of
> source code from the Python Developer's Handbook by Andre Lessa and the
> PyGTK Tutorial. That is where these source codes came from.
>
> The code in Question came from the Chapter Getting Started in the PyGTK
> Tutorial[/color]

Note that the code you wrote was incorrectly indented. The original
code[1] was *correctly* indented and ought to work.
[color=blue]
> and from Chapter 15, page 579 in the Python Developer's
> Handbook.[/color]

I *have* heard that this book contains many errors.

[1]

http://www.moeraki.com/pygtktutorial/pygtk2tutorial/ch-GettingStarted.html#sec-HelloWorld

--
Robert Kern
rkern@ucsd.edu

"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter

**Coral Snake** · Jul 18 '05, 10:24 PM

Re: Mysterious "Attrib ute Errors" when GUI Programming

Again Thanks to everyone here. Both the GTK and the Tkinter example are
running fine now.

Mysterious "Attribute Errors" when GUI Programming

Mysterious "Attribute Errors" when GUI Programming

Comment

Comment

Comment

Comment

Comment

Comment