Here is how to parse command-line options of types:
--opt=value
--no-opt
--opt
in a really quick way without any modules like Getopt
Despite of its small code size, it supports default values, complaints about undefined options, YES/NO-style options.
my %opts = (
  # %known_opts enumerates allowed opts as well as specifies default
  #   and initial values
  my %known_opts = (
     'debug' => 0,
     'verbose' => 1,
     'log' => 'log.txt', # default value
     'file' => '',       # actually like declaration of option
  ),
  #options itself
  my %specified_opts = (
    (map {/^--([\-_\w]+)=(.*)$/} @ARGV),      # --opt=smth
    (map {/^no-?(.*)$/i?($1=>0):($_=>1)} map {/^--([\-_\w]+)$/} @ARGV)
+,  # --opt --no-opt --noopt
  ),
);
die "option '$_' is not recognized" for grep {!exists $known_opts{$_}}
+ keys %specified_opts;
@ARGV = grep {!/^--/} @ARGV;
# then normal program goes here

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In reply to alternate parsing method for options by svad

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