Special name for an argument to a [proc] - if it's last in the argument list, it will contain a list (possibly empty) of all the remaining arguments. proc demo {first {second "none"} args} { puts "first = $first" puts "second = $second" puts "args = $args" } demo one demo one two demo one two three four five results in: first = one second = none args = first = one second = two args = first = one second = two args = three four five ---- '''example args''' Class Club -parameter {id {name unknown}} Class Player -superclass Club -parameter {{name unknown} {position unknown}} Player proc show_players args { if { [string length $args] == 0} { puts "Show players DB" foreach p [my info instances] { puts "[$p name] [$p position]" } return } set pos [string toupper $args] puts "Players with postition $pos:" foreach p [my info instances] { foreach char [split $pos {}] { if {[string first $char [$p position]] == 1} { puts "[$p name] [$p position]" break } } } } ---- Is it just me, or is that a pretty poor example of args? You do [[string length $args]] and [[string toupper $args]] but you firmly established that args is a list, not a string. It is generally accepted as bad practice to perform string operations on lists. [LES] But, if [everything is a string], aren't lists strings too? On the other hand, there has been quite some debate on whether '''everything is a list''' rather than a string... [LV] I don't know that I would go so far as saying that it is ''bad practice to perform string operations on lists''. I would say that it is generally bad practice to perform list operations on variables known only to have strings. And I would say that '''some''' string operations on lists may result in results that , at first blush, one might not expect. [Lars H]: The problem with applying string operations on known [pure list]s like $args is basically [shimmering]. Applying a string operation will require generation of a string representation, and the cost for that (in memory and processing time) is often better avoided whenever possible. If you pass multi-megabyte lists around (something Tcl 8 handles beautifully well), you probably don't want to double the memory footprint by also generating their string representations. An extreme example: set val x for {set n 1} {$n<=64} {incr n} {set val [list $val $val]} puts "Tcl will get this far."; flush stdout string length $val puts "But it runs out of memory before it gets this far.!" [LV] So then the example isn't a poor example of args - but a poor example of good performance. ---- [MG] offers a quick example off the top of his head (and therefore untested), on his way through... proc randomCmd {args} { set error {wrong # args: should be "randomCmd ?-arg value ...? string"} set num [llength $args] if { $num == "0" || [expr {($num%2)==0}] } { error $error; } array set opts [list -width 5 -height 5 -fg [list] -bg [list] -foreground blue -background red] if { $num > 1 } { foreach {x y} [lrange $args 0 end-1] { if { ![info exists opts($x)] } { error "unknown option \"$x\""; } set opts($x) $y } } foreach {x y} [list -fg -foreground -bg -background] { if { [llength $opts($x)] > 0 } { set opts($y) $opts($x) } unset opts($x) } } echo "String is \"[lindex $args end]\". Apply these options: [array get opts]" } ---- [LV] Here's where I am trying to use args - maybe someone has a suggestion. My code is this: % proc d {name args} { puts "DEBUG: $name: $args" } % d mainline "this is the first spot in the mainline" DEBUG: mainline: {this is the first spot in the mainline} That is to say, it is intended as a place to control debug statements. I can just return rather than do the puts, to turn off the debugging. HOWEVER, the debugging output looks peculiar. Not a problem - it is just for debugging. But if I were going to use this for something else, I wouldn't want the extra {} in there. [RS]: try [join] $args to get rid of braces :) ---- See also [magic names]. ---- [Category Documentation]