I use this proc to parse a proc's args and allow any parameter to be
specified as a switch [JBR].  

-----

To redefine proc so that all procs are "procargs" enabled:

   procargs proc

To "procargs" enable an existing proc

   procargs existingprocname 

To define a proc with "procargs" enabeled

   procargs proc { args } { body }

-----

I also use it as a replacement for getopt and friends.  I write the 
main function of the scripted command as a proc and then eval that 
proc at the bottom of the file with $argv.

   procargs main { parameter list here } {
	...
   }
  
   eval main $argv

-----
Here is the proc:


 interp alias {} _proc {} proc

 proc _procargs { __name __params __args } {
    set __nargs [llength $__args]
    set __npars [llength $__params]

    # Set the defaults
    #
    foreach __par $__params {
        set __param     [lindex $__par 0]
        set __value     [lindex $__par 1]

        if { ![string compare $__par args] } {
            set __acat 1
            break
        }

        upvar $__param $__param
        set   $__param $__value
        lappend __paramnames $__param
    }

    # Set the args
    #
    set __p   0
    set __eoo 0
    for { set __i 0 } { $__i < $__nargs } { incr __i } {
        set __arg [lindex $__args $__i]

        if { $__eoo } {
            set __pnum $__p
            incr __p
        } else {
            switch -regexp -- $__arg {
             ^$         -
             ^-[0-9.]+$ -
             ^[^-].*$  {
                set __pnum $__p
                incr __p
             }
             default {
                if { ![string compare $__arg "--"] } {
                    set __eoo 1
                    continue
                }
                set __pnum [lsearch $__paramnames [string range $__arg 1 end]]
                if { $__pnum < 0 } {
                    error "$name: no option $__arg: must be one of: $__paramname
                }
                set arg [lindex $__args [incr __i]]
             }
            }
        }

        set __param [lindex $__paramnames $__pnum]
        set $__param $__arg
    }
 }

 proc  procargs { args } {
        _procargs procargs { name params body } $args

    if { ![string compare $name proc] } {
        rename _proc     {}
        rename  proc     _proc
        rename  procargs  proc

        return
    }

    if { [llength [info commands $name]] && ![string compare $body {}] }  {
        set args [info args $name]
        set body [info body $name]

        # rebuild params
        #
        foreach arg $args {
            if { [info default $name $arg value] } {
                lappend params "$arg $value"
            } else {
                lappend params "$arg"
            }
        }
    }

    _proc $name { args } "_procargs $name [list $params] \$args; $body"
 }