Tk Listbox - Selected Item ?

[Martin Franklin]

Peter Moscatt wrote:
> Martin Franklin wrote:
> 
> 
>>Peter Moscatt wrote:
>>
>>>I am having trouble understanding the methods for the Listbox from Tk.
>>>
>>>If I was to select at item in the list using a mouse click (have already
>>>created the bind event) - what method returns the text of the selected
>>>item ?
>>>
>>>Pete
>>>
>>
>>
>>Pete,
>>
>>pydoc Tkinter.Listbox
>>
>><snip>
>>
>>  |  curselection(self)
>>  |      Return list of indices of currently selected item.
>>  |
>>  |  delete(self, first, last=None)
>>  |      Delete items from FIRST to LAST (not included).
>>  |
>>  |  get(self, first, last=None)
>>  |      Get list of items from FIRST to LAST (not included).
>>
>>So to get the value of the selected item:
>>
>>lb.get(lb.curselection()[0])
>>
>>
>>provided the listbox is in single selection mode or only one item is
>>selected
>>
>>Martin
> 
> 
> Thanks Martin,
> 
> I used the:
>   lb.get(lb.curselection()[0])
> 
> ant this works to a point.  When I select the item in the listbox the system
> generates an error:
> 
> Exception in Tkinter callback
> Traceback (most recent call last):
>   File "/usr/lib/python2.3/lib-tk/Tkinter.py", line 1345, in __call__
>     return self.func(*args)
>   File "/home/linux/programming/dxcluster/servers.py", line 37, in sel
>     items = self.listbox.get(self.listbox.curselection()[0])
> IndexError: tuple index out of range
> 
> 
> Then if I select a second time directly after the error message I get my
> desired result.
> 

Pete,

Sounds like you are using the wrong kind of bind event. That is the
first time you select an item the callback for the bind command is
called *before* the selection is made.  Can you post the code you have
showing the bind method and callback?

This code shows three different bind methods, the first produces the
same exception that you got...


from Tkinter import *


root = Tk()
lb = Listbox(root)
lb.insert(0, "one")
lb.insert(0, "two")
lb.insert(0, "three")
lb.pack()

def callback(*event):
     print lb.get(lb.curselection()[0])

## BAD
#~ lb.bind("<1>", callback)

## OK
#~ lb.bind("<ButtonRelease-1>", callback)

## Best
lb.bind("<<ListboxSelect>>", callback)

root.mainloop()


The <<ListboxSelect>> is a virtual event I think quick google would tell
you more and the Tk man pages (online) have a complete explanation...

http://www.tcl.tk/man/tcl8.4/TkCmd/listbox.htm
http://www.tcl.tk/man/tcl8.4/TkCmd/listbox.htm#M60


Cheers,
Martin.