Data::OptList - parse and validate simple name/value option pairs

version 0.107

  use Data::OptList;

  my $options = Data::OptList::mkopt([
    qw(key1 key2 key3 key4),
    key5 => { ... },
    key6 => [ ... ],
    key7 => sub { ... },
    key8 => { ... },
    key8 => [ ... ],
  ]);

...is the same thing, more or less, as:

  my $options = [
    [ key1 => undef,        ],
    [ key2 => undef,        ],
    [ key3 => undef,        ],
    [ key4 => undef,        ],
    [ key5 => { ... },      ],
    [ key6 => [ ... ],      ],
    [ key7 => sub { ... },  ],
    [ key8 => { ... },      ],
    [ key8 => [ ... ],      ],
  ]);

Hashes are great for storing named data, but if you want more than one entry for a name, you have to use a list of pairs. Even then, this is really boring to write:

  $values = [
    foo => undef,
    bar => undef,
    baz => undef,
    xyz => { ... },
  ];

Just look at all those undefs! Don't worry, we can get rid of those:

  $values = [
    map { $_ => undef } qw(foo bar baz),
    xyz => { ... },
  ];

Aaaauuugh! We've saved a little typing, but now it requires thought to read, and thinking is even worse than typing... and it's got a bug! It looked right, didn't it? Well, the xyz => { ... } gets consumed by the map, and we don't get the data we wanted.

With Data::OptList, you can do this instead:

  $values = Data::OptList::mkopt([
    qw(foo bar baz),
    xyz => { ... },
  ]);

This works by assuming that any defined scalar is a name and any reference following a name is its value.

  my $opt_list = Data::OptList::mkopt($input, \%arg);

Valid arguments are:

  moniker        - a word used in errors to describe the opt list; encouraged
  require_unique - if true, no name may appear more than once
  must_be        - types to which opt list values are limited (described below)
  name_test      - a coderef used to test whether a value can be a name
                   (described below, but you probably don't want this)

This produces an array of arrays; the inner arrays are name/value pairs. Values will be either "undef" or a reference.

Positional parameters may be used for compability with the old mkopt interface:

  my $opt_list = Data::OptList::mkopt($input, $moniker, $req_uni, $must_be);

Valid values for $input:

 undef    -> []
 hashref  -> [ [ key1 => value1 ] ... ] # non-ref values become undef
 arrayref -> every name followed by a non-name becomes a pair: [ name => ref ]
             every name followed by undef becomes a pair: [ name => undef ]
             otherwise, it becomes [ name => undef ] like so:
             [ "a", "b", [ 1, 2 ] ] -> [ [ a => undef ], [ b => [ 1, 2 ] ] ]

By default, a name is any defined non-reference. The name_test parameter can be a code ref that tests whether the argument passed it is a name or not. This should be used rarely. Interactions between require_unique and name_test are not yet particularly elegant, as require_unique just tests string equality. This may change.

The must_be parameter is either a scalar or array of scalars; it defines what kind(s) of refs may be values. If an invalid value is found, an exception is thrown. If no value is passed for this argument, any reference is valid. If must_be specifies that values must be CODE, HASH, ARRAY, or SCALAR, then Params::Util is used to check whether the given value can provide that interface. Otherwise, it checks that the given value is an object of the kind.

In other words:

  [ qw(SCALAR HASH Object::Known) ]

Means:

  _SCALAR0($value) or _HASH($value) or _INSTANCE($value, 'Object::Known')

  my $opt_hash = Data::OptList::mkopt_hash($input, $moniker, $must_be);

Given valid mkopt input, this routine returns a reference to a hash. It will throw an exception if any name has more than one value.

Both mkopt and mkopt_hash may be exported on request.

Ricardo Signes <rjbs@cpan.org>

This software is copyright (c) 2006 by Ricardo Signes.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.