The option-declaring functions want to store the declarations in an array with a globally accessible name. For compatibility with older software, the name of this array can not be passed as a parameter. Consequently, your script must declare it before sourcing cmdline.cli.

A call like

   setSpec ::main

declares ::main as the database (array) to be filled by subsequent calls to ::clig::Flag and the like. The array should not contain anything except entries created with the declarator functions.

After declaring the database and sourcing your declarations from cmdline.cli your script is ready to call parseCmdline. This is typically done with:

  set Program [file tail $argv0]
  if {[catch {parseCmdline ::main $Program $argc $argv} err]} {
    puts stderr $err
    exit 1
  }

If parseCmdline finds an unknown option in $argv, it prints a usage-message to stderr and exits the script with exit-code 1. If it finds any other errors, like numerical arguments being out of range, it prints an appropriate error-message to stderr and also exits your script with code 1. Setting Program and passing it to parseCmdline instead of $argv0 results in nicer error-messages.

If no errors occur, parseCmdline enters the values found into variables of its callers context. The names of these variables are those declared with the declarator functions. For example with a declaration like

  Float -ival ival {interval to take into account} -c 2 2 

the caller will find the variable ival set to a list with 2 elements, if option -ival was found with two numeric arguments in $argv.

If option -ival is not existent on the given command line, ival will not be set. Consequently, it is best to not set the declared variables to any value before calling parseCmdline.

The typical skeleton of your script should look like

  package require clig
  namespace import ::clig::*
  
  setSpec ::main
  source [file join path to your installed base cmdline.cli]
  set Program [file tail $argv0]
  if {[catch {parseCmdline ::main $Program $argc $argv} err]} {
    puts stderr $err
    exit 1
  }