package for parsing argument in TCL

Question

Does anyone know a standard package for tcl to easily parse the input arguments ? or a ready proc ? ( I have only 3 flags but something general is preferable ).

Answer 1

Here is a simple, native, no-package argument parser:

#
# arg_parse simple argument parser
# Example `arg_parse {help version} {with-value} {-with-value 123 positional arguments}`
# will return:
# `positionals {positional arguments} with-value 123`
#
# @param boolean_flags flags which does not requires additional arguments (like help)
# @param argument_flags flags which requires values (-with-value value)
# @param args the got command line arguments
#
# @return stringified array of parsed arguments
#
proc arg_parse { boolean_flags argument_flags args } {
    set argsarr(positionals) {}

    for {set i 0} {$i < [llength $args]} {incr i} {
        set arg [lindex $args $i]
        if { [sstartswith $arg "-" ] } {
            set flag [string range $arg 1 end]
            if { [lsearch $boolean_flags $flag] >= 0 } {
                set argsarr($flag) 1
            } elseif { [lsearch $argument_flags $flag] >= 0 } {
                incr i
                set argsarr($flag) [lindex $args $i]
            } else {
                puts "ERROR: Unknown flag argument: $arg"
                return
            }
        } else {
            lappend argsarr(positionals) $arg
        }
    }
    return [array get argsarr]
}

USE argument parser

#
# USE argument parser:
#
proc my_awesome_proc { args } {
    array set argsarr [arg_parse "help version" "with-value" {*}$args]
    parray argsarr
}

USE my_awesome_proc :

% my_awesome_proc -help
argsarr(help)        = 1
argsarr(positionals) = 
% my_awesome_proc -with-value 123
argsarr(positionals) = 
argsarr(with-value)  = 123
% my_awesome_proc -wrong
ERROR: Unknown flag argument: -wrong
% my_awesome_proc positional arguments
argsarr(positionals) = positional arguments
%