Tkinter: "Get root for a widget" is private?

Randall Hopper aa8vb at yahoo.com
Wed Apr 5 18:42:58 CEST 2000


Jeff Senn:
 |Randall Hopper <aa8vb at yahoo.com> writes:
 |> I have a timer class built around Tk timers.  I realize I could just pass
 |> any_old_widget into this routine, and it would store it off into state data
 |> and use it periodically to access the 'after' and 'after_cancel' methods.
 |> 
 |> However, this timer has nothing to do with this widget in particular, so
 |> why should it have a reference to it (versus the button next to it, or the
 |> list widget below it)?  It makes more sense for the timer class to accept
 |> and bookmark the root object.  This root is associated with the global Tk
 |> state, and it makes sense for a timer to bookmark this to use global Tk
 |> state commands.
 |
 |Unless you're doing something wacky (creating multiple roots??), you
 |could just do what Tkinter itself (generally) does and use
 |Tkinter._default_root to get the instance of the root object....

Right.  I'm using _root() now which works.  My original point wasn't that I
couldn't get root from a widget, but that to do it I violate the declared
public/private/protected policy for Tkinter.  Since Python has no enforced
access control, I can poke at object internals anytime, but I really want
to avoid this.

My understanding is that .<symbol> is public, ._<symbol> is protected, and
.__<symbol> is private.

If _root() was ripped out in the next version of Python, I wouldn't have a
leg to stand on.  And by all rights it's protected so removing it should
not affect me (or any other external code), unless I (or it) was deriving
off this class.

As Fredrik mentioned I could just snitch global Tk commands off
any_old_widget, but an event loop timer object that has nothing to do with
"any" widget shouldn't be keeping a handle to any_old_widget.  That's not
clean code.

An alternative is just to pass root around everywhere, but that seems silly
if every widget already knows its root.

So my request was for _root() to be declared public (e.g. as .root())

-- 
Randall Hopper
aa8vb at yahoo.com




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