Some oddities in 2.3b1, esp. with Tkinter

["Martin v. Löwis"]

Russell E. Owen wrote:
> 1) A filter to remove fonts with non-ascii names (used to filter out 
> stuff that I could not display in a pop-up menu) broke.
>             try:
>                 unicode(fontName, 'ascii', 'strict')
>                 return True
>             except UnicodeError:
>                 return False
> 
> Python 2.2 throws UnicodeError. Python 2.3b1 throws TypeError. The fix 
> is trivial (e.g. "except (UnicodeError, TypeError)". The filter is 
> probably not needed anymore anyway, since Tk 8.4.2 can apparently 
> display menu items with non-ascii characters.

I don't understand. Why do you ever need to convert the *font name*
to a Unicode string, or why would Python ever fail to do so? Font
names are ASCII only, all the time, so you can't possibly ever get
an exception here.

> 2) Tk file events are no longer supported:
> 
> RuntimeError: _tkinter.createfilehandler not supported for threaded Tcl
> 
> This is painful since it's hard to see how to write a proper networking 
> GUI with Tkinter without file events for reading data. Perhaps I can get 
> them back again by disabling the new threaded tcl support.

Are you using Debian by any chance? Otherwise, you should not see
a threaded Tcl.

If your Tcl installation is threaded, you should use 
tkapp.createfilehandler instead.

> 3) Tk returning things as objects is nice, but I had this break at least 
> one thing of mine and it will break others (see 4 below):
> 
> I was assuming that the values in the dictionary returned by 
> tkFont.Font.config() were strings. Fortunately this was easy to fix. A 
> bit disconcerting -- I wonder how many any other little pitfalls like 
> this still buried in my code -- but well worth the cost of the change.

What is the nature of that change?

> Example:
> v = StringVar()
> v is a <Tkinter.StringVar instance at 0x2c98a0>
> l = Label(textvariable=v)
> x = l["textvariable"]
> x is reported as a <namespaceVarName object at 0x0168b048>
> but is a _tkinter.Tcl_Obj based on the following traceback:
> root.getvar(x)
> Traceback...
> TypeError: getvar() argument 1 must be string, not _tkinter.Tcl_Obj

Please submit a bug report. This is easy to fix (just invoke
str() of the Tcl_Obj)

> 5) Note that Tkinter's handling of font objects does not seem to have 
> changed. I was hoping it would start returning font objects instead of 
> strings, or offer some way to convert the string to a font object, but 
> apparently not:

Does Tk have the notion of "font objects"?

Regards,
Martin