Implementing it makes this "crazy" check in
http://bugs.python.org/issue3767
(http://bugs.python.org/file12043/tkColorChooser.diff) be no longer needed

The patch changes _tkinter.c so can a C guru take a look please.

I'd call this a new feature;  removing 2.7 and 3.1 from versions.

The patch needs updating for py3k, which should be a fairly simple task.

I don't know much about Tcl, but wouldn't this change give quite confusing results for numeric values?  Presumably, all integers and floats would have a bool() of True?  (Or am I misunderstanding?)  I'm not sure what the value of implementing __nonzero__ is if it only works as expected for strings.

Mark,

If you want to expand it to handle other data types, I'm ok with it
but I predict troubles for you. The problem is that in Tcl there is
only one "real" data type -- string. Depending on how you operate over
a value it is then, internally, treated as something more specific but
this is not directly exposed for the "API users".

> If you want to expand it to handle other data types, I'm ok with it
> but I predict troubles for you.

Yes, I suspected as much.  I don't know much Tcl, but I'm definitely prepared to believe you on this point. :)  I'd be fine with this patch if there's some documentation somewhere that points out that the bool() might give unexpected results (for Python users) for zeros, empty lists, etc.

I assume that Tcl_GetCharLength works for any object, regardless of its internal representation?

Can you update the patch for py3k, and add docs and tests?

> I assume that Tcl_GetCharLength works for any object, regardless of
> its internal representation?

I didn't look at its code but I assume it will create a string representation for the object in question if there isn't one in place when the call happens, so this means I /believe/ it will work for any Tcl object.

> Can you update the patch for py3k, and add docs and tests?

I can do it (maybe the test part may not be excellent), but not at this moment.

Btw, I'm happy that you mentioned that doc requirement about unexpected results because I was going to write about it in my previous reply but I thought my English could hurt its meaning and negatively affect you.

I'm closing the issue. People who want to check for an empty string representation can just convert the tcl objects to strings themselves. I agree with Mark that implementing nonzero is too ambiguous.