[Tkinter-discuss] optionmenu insert
klappnase at web.de
Wed May 3 11:29:12 CEST 2006
On Tue, 02 May 2006 14:32:17 +0200
Pavel Kosina <geon at post.cz> wrote:
> Just found there is another trouble with this. Maybe I could help
> myself, but dont know how to get from tk documentation what you have
> written - how to know why "command" should be there, why ["menu"], etc.
the "menu" key is created in Tkinter's OptionMenu class to give us access
to the Menu subwidget; optionmenu["menu"] is equivalent with optionmenu.__menu .
"command" is there to tell tk what to insert into the menu; try:
and you get a TclError:
_tkinter.TclError: bad menu entry type "blah": must be cascade, checkbutton, command, radiobutton, or separator
> Anyway, I have:
> w = OptionMenu(root, var,u"one", u"two", u"...",command=ok)
> w["menu"].insert(2, "command", label=u"three")
> When I choose "three" then, the function 'ok' is not called. It must be
> another argument in last line, I think.
Oops, you are right. A look at Tkinter.OptionMenu shows that it is not that trivial.
Tkinter wraps the command in its internal _setit class, so it should actually be:
from Tkinter import _setit
w['menu'].insert('end', 'command', label='blah', command=_setit(var, 'blah', ok))
The arguments for the _setit constructor are: _setit(variable, value, callback) .
Not very nice, indeed. Maybe it would be a nice improvement to Tkinter to add at least
an insert() and a delete() method to Tkinter.OptionMenu .
If you do not want to use the "hidden" _setit() you might define another callback for the inserted items:
w['menu'].insert('end', 'command', label='blah', command=lambda : ok_new('blah'))
Maybe it is even nicer not to use an OptionMenu command at all and use a trace callback for the variable instead:
>>> v = StringVar()
>>> def ok(*args):
... print v.get()
>>> v.trace('w', ok)
>>> om = OptionMenu(r, v, 'a', 'b', 'c')
>>> om['menu'].insert('end', 'command', label='foo', command=lambda : v.set('foo'))
At least you do not need a second callback this way.
I hope this helps
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