Code:

proc proc1 {string1 string2 args} { #Instantiate option-variables  set nocase 0 #Do we have any options to care for? if {[llength $args] > 0} {  #Iterate through the whole list of options...  foreach arg $args {   #... and parse each to see if they're valid or not.   #Use the "default" keyword to catch any unknown options and bail out.   switch -- $arg {    "-nocase" {     set nocase 1    }    default {     error "Unknown option \"$arg\""    }   }  } } #All options (if any) parsed, and option-variables properly updated, # lets do the actual work now ...}