NAME
====

Hash2Class - A role to create class instances out of a Hash

SYNOPSIS
========

```raku
  use Hash2Class;

  class UpdateInfo does Hash2Class[
    added   => Date(Str),
    changed => Date(Str),
  ] { }

  class FBB does Hash2Class[
    foo        => Str,
    bar        => Int,
    baz        => UpdateInfo,
    '@bazlist' => UpdateInfo,
    '%bazmap'  => UpdateInfo,
  ] { }

  my %hash =
    foo => "foo",
    bar => 42,
    baz => {
      added   => "2020-07-18",
      changed => "2020-07-19",
    },
    bazlist => [
      { added => "2020-07-14", changed => "2020-07-15" },
      { added => "2020-07-16", changed => "2020-07-17" },
    ],
    bazmap => {
      first  => { added => "2020-07-01", changed => "2020-07-02" },
      second => { added => "2020-07-03", changed => "2020-07-04" },
      third  => { added => "2020-07-05", changed => "2020-07-06" },
    },
  ;

  my $fbb = FBB.new(%hash);
  dd $fbb.foo;                    # "foo"
  dd $fbb.bar;                    # 42
  dd $fbb.bazlist[1].added;       # Date.new("2020-07-01")
  dd $fbb.bazmap<third>.changed;  # Date.new("2020-07-06")
```

DESCRIPTION
===========

The `Hash2Class` role allows one to create a class from a parameterization of the role. The parameterization consists of a list of `Pair`s in which the key indicates the name of key in the hash, and the value indicates the type the value in the hash is supposed to have, or be coerced to. The key becomes the name of a method accessing that key in the hash.

A key can be prefixed with `@` to indicate an Array of values in the hash, or be prefixed with `%` to indicate a hash, or `$` to indicate a scalar value (which is the default).

The types specified can **also** be classes created by the `Hash2Class` role, so recursive structures are possible, as long as they are defined in the correct order.

Classes made with the `Hash2Class` role are instantiated by calling `.new` with a hash as its only parameter. Such a hash is typically the result of rakufication of a `JSON` blob (e.g. with `from-json` of the [JSON::Fast](JSON::Fast) module). But the hash can be created in any manner.

Values are checked lazily, so no work is done on parts of the hash that are not accessed.

AUTHOR
======

Elizabeth Mattijsen <liz@wenzperl.nl>

Source can be located at: https://github.com/lizmat/Hash2Class . Comments and Pull Requests are welcome.

COPYRIGHT AND LICENSE
=====================

Copyright 2020 Elizabeth Mattijsen

This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.

