ordering=

Set the handling of the ordering of options and arguments. A RuntimeError is raised if option processing has already started.

The supplied value must be a member of GetoptLong::ORDERINGS. It alters the processing of options as follows:

REQUIRE_ORDER :

Options are required to occur before non-options.

Processing of options ends as soon as a word is encountered that has not been preceded by an appropriate option flag.

For example, if -a and -b are options which do not take arguments, parsing command line arguments of '-a one -b two' would result in 'one', '-b', 'two' being left in ARGV, and only ('-a', '') being processed as an option/arg pair.

This is the default ordering, if the environment variable POSIXLY_CORRECT is set. (This is for compatibility with GNU getopt_long.)

PERMUTE :

Options can occur anywhere in the command line parsed. This is the default behavior.

Every sequence of words which can be interpreted as an option (with or without argument) is treated as an option; non-option words are skipped.

For example, if -a does not require an argument and -b optionally takes an argument, parsing '-a one -b two three' would result in ('-a','') and ('-b', 'two') being processed as option/arg pairs, and 'one','three' being left in ARGV.

If the ordering is set to PERMUTE but the environment variable POSIXLY_CORRECT is set, REQUIRE_ORDER is used instead. This is for compatibility with GNU getopt_long.

RETURN_IN_ORDER :

All words on the command line are processed as options. Words not preceded by a short or long option flag are passed as arguments with an option of '' (empty string).

For example, if -a requires an argument but -b does not, a command line of '-a one -b two three' would result in option/arg pairs of ('-a', 'one') ('-b', ''), ('', 'two'), ('', 'three') being processed.