TIP #323: Do Nothing Gracefully , by Colin McCormack, Donald Porter, and Kevin Kenny, and implemented in Tcl version Changes in Tcl/Tk 8.6, provides the rationale for commands that do do nothing under certain circumnstances.
With the advent of the {*} operator which expands an empty list into nothing at all, it became clear that it would be useful in various cases if commands that normally accept variable number of arguments at the end of the command could handle the case of no arguments at all being passed. The TIP modified the following commands: