TIP #323: Do Nothing Gracefully

TIP #323: Do Nothing Gracefully , by Colin McCormack, Donald Porter, and Kevin Kenny, and implemented in Tcl version 8.6, provides the rationale for commands that do nothing under certain circumstances.

Description

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:

file delete

Accept zero pathnames.

file mkdir

Accept zero directories.

global

Accept zero variable names.

glob

Accept zero patterns and return a no matches error, or when -nocomplain is provided, return a list of zero matching files.

lassign

Accept zero variable names [L1 ].

linsert

Accpet zero elements [L2 ].

lrepeat

Accept both a number of 0, and zero elements [L3 ].

my variable

Accept zero variable names.

namespace upvar

Accept zero variable names

::tcl::tm::path add

Accept zero paths.

::tcl::tm::path::remove

Accept zero paths.

variable

Accept zero variable names [L4 ].