Template Script - 2023.1 English

Below is a template script based on the notions that been introduced earlier. It illustrates:

1. Usage of a private namespace to avoid polluting the global namespace (lshift is only available inside the namespace foo).
2. Handling of command line arguments (including -help and -version to provide a version of the script).
3. Usage of return -error (or error) command to generate Tcl errors when it is needed.

   namespace eval foo {
     namespace export myproc
     variable version 1.0
   }
   proc foo::lshift listVar {
       upvar 1 $listVar L
       set r [lindex $L 0]
       set L [lreplace $L [set L 0] 0]
       return $r
   }
   proc foo::myproc { args } {
     #-------------------------------------------------------
     # Process command line arguments
     #-------------------------------------------------------
     set error 0
     set help 0
     set verbose 0
     set ports {}
     # if {[llength $args] == 0} { incr help }; # Uncomment if necessary
     while {[llength $args]} {
       set flag [lshift args]
       switch -exact -- $flag {
         -p -
         -ports {
              set ports [lshift args]
         }
         -v -
         -verbose {
              set verbose 1
         }
         -h -
         -help {
              incr help
         }
         -version {
              variable version
              return $version
         }
         default {
              if {[string match "-*" $flag]} {
                puts " ERROR - option '$flag' is not a valid option."
                incr error
              } else {
                puts "ERROR - option '$flag' is not a valid option."
                incr error
              }
         }
       }
     }
     if {$help} {
   set callerflag [lindex [info level [expr [info level] -1]] 0]
       # <-- HELP
       puts [format {
     Usage: %s
                 [-ports|-p <listOfPorts>]
                 [-verbose|-v]
                 [-version]
                 [-help|-h]
     Description: xxxxxxxxxxxxxxxxxxx.
                  xxxxxxxxxxxxxxxxxxx.
     Example:
        %s -port xxxxxxxxxxxxxxx
   } $callerflag $callerflag ]
       # HELP -->
       return -code ok {}
     }
     # Check validity of arguments. Increment $error to generate an error
     if {$error} {
       return -code error {Oops, something is not correct}
     }
     # Do something
     return -code ok {}
   }