Is there a limit on the length or nesting of Tcl/Tk widget pathnames?

Question

Is there a limit on the length or nesting of Tcl/Tk widget pathnames?

For example:

ttk::button .a.b.c -text "Hello World"
pack .a.b.c

creates button .a.b.c inside container .a.b which is inside .a, etc. Is there a limit to the identifier names and nesting level? For example if i rewrote it thus:

ttk::button .extralonga.extralongb.extralongc -text "Hello World"
pack .extralonga.extralongb.extralongc

How long can i go before hitting problems?

Answer 1

Tk itself imposes no such limits at all (though you could have problems if you end up using very large amounts of memory).

The underlying graphics layer might impose limits, I suppose, but I've never encountered them. (Note that from the perspective of that layer, it is only the path within a toplevel that counts.) I guess it's more likely that you'll create an unworkable mess and impractical GUI long before you hit any limits that exist; I tend to try to keep the level of nesting fairly small; using grid rather than pack helps in this, as does making interaction widgets direct children of the toplevel and using the -in option to the geometry managers to set things up right. In fact, I think the only thing that must be correct in terms of parent/child relationships with widgets is where you need the clipping; in Tk, children are clipped by their parents. (This matters if you're using a text or canvas to do different types of scrollable areas, or — IIRC — when using ttk::notebook to overlay several widgets on the one area.)

Summary: Worry about other problems first, OK?