para

use v6.d;

role ValueType:ver<0.0.4>:auth<zef:lizmat> {
    has $!WHICH;

    my @attributes = ::?CLASS.^attributes.grep: *.name ne 'WHICH';

    multi method WHICH(::?CLASS:D: --> ValueObjAt:D) {
        $!WHICH.defined
          ?? $!WHICH
          !! self!WHICH
    }

    method !WHICH() {
        my str @rest = self.^name;
        for @attributes -> $attribute {
            my $WHICH := $attribute.get_value(self).WHICH;
            $WHICH ~~ ValueObjAt
              ?? @rest.push($WHICH.Str)
              !! die "Attribute '$attribute.name()' is not a Value Type";
        }
        $!WHICH := ValueObjAt.new(@rest.join('|'))
    }
}



head

ValueType - A role to create Value Type classes


class Point does ValueType {
    has $.x = 0;
    has $.y = 0;
}


say Point.new.WHICH;  # Point|Int|0|Int|0


# fill a bag with random Points
my $bag = bag (^1000).map: {
  Point.new: x => (-10..10).roll, y => (-10..10).roll
}
say $bag.elems;  # less than 1000


The ValueType role mixes the logic of creating a proper ValueType into a
class.  A class is considered to be a value type if the C<.WHICH> method
returns an object of the C<ValueObjAt> class: that then indicates that
objects that return the same C<WHICH> value, are in fact identical and
can be used interchangeably.


This is specifically important when using set operators (such as C<(elem)>,
or C<Set>s, C<Bag>s or C<Mix>es, or any other functionality that is based
on the C<===> operator functionality, such as C<unique> and C<squish>.


The format of the value that is being returned by C<WHICH> is only valid
during a run of a process.  So it should B<not> be stored in any permanent
medium.


The first time the C<WHICH> method (mixed in by this role) is called, it
will check all of its attribute values for being a value type.  If they
all are, then it will construct a C<ValueObjAt> object for its C<WHICH>
value, save it for future reference, and return it.  If any of the attribute
values are B<not> a value type, then an exception will be thrown.


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


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


root

README

React

=begin React :component<HeaderCol> :id<menu> 
=para L<Documentation|/doc/introduction>
=para L<Modules| /mods>
=para L<Examples| file:../examples/index.podlite>
=para L<Download |file:../download/index.podlite>
=para L<About|file:../about/index.podlite>
=para 🔍 K<⌘K>/K<ctrl-K>
=end React


=begin React :component<HeaderCol> :id<footer>  
=begin nested :!nested
=item1 B<Language>
    =item2 L<Get started|file:../getting-started/getting-started.podlite>
    =item2 L<Why Raku?|/doc/language/faq#Why-should-I-learn-Raku-What's-so-great-about-it>
    =item2 L<Try Raku|https://glot.io/new/raku>
    =item2 L<Raku cheat sheet|https://github.com/Raku/mu/blob/master/docs/Perl6/Cheatsheet/cheatsheet.txt>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<Raku on Exercism|https://exercism.org/tracks/raku>
    =item2 L<Wikipedia|https://en.wikipedia.org/wiki/Raku_(programming_language)>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>

=end nested
=begin nested :!nested

=item1 B<L<Documentation|/doc>>
    =item2 L<Getting started, Migration guides from other languages, & Tutorials | file:../doc/introduction.podlite>
    =item2 L<Language References|file:../doc/reference.podlite>
    =item2 L<Type Reference| file:../doc/types.podlite>
    =item2 L<Miscellaneous| file:../doc/miscellaneous.podlite>
    =item2 L<FAQs (Frequently Asked Questions)|/doc/language/faq>
    =item2 L<Community|/doc/language/community>
    =item2 L<The list of all documents|file:../doc/index.podlite>

=item1 B<Resources>
    =item2 L<The Raku Guide|https://raku.guide/>
    =item2 L<Books |https://perl6book.com/>
    =item2 L<Rosetta Code | https://www.raku.org/community/rosettacode>

=end nested
=begin nested :!nested

=item1 B<Resoures>
    =item2 L<Download | file:../download/index.podlite>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>

=item1 B<Learning>
    =item2 L<The Raku Guide|https://raku.guide/>
    =item2 L<Wikibook |https://en.wikibooks.org/wiki/Raku_Programming>
    =item2 L<Books |https://perl6book.com/>
    =item2 L<Rosetta Code | https://www.raku.org/community/rosettacode>
    =item2 L<Learn Raku in Y minutes|https://learnxinyminutes.com/docs/raku/>
    =item2 L<Golfing |https://github.com/AlexDaniel/raku-golf-cheatsheet>
=end nested
=begin nested :!nested

=item1 B<Explore>
    =item2 L<Raku Blog Aggregator|https://planet.raku.org/>
    =item2 L<Rakudo Weekly|https://rakudoweekly.blog/>
    =item2 L<The Weekly Challenge |https://perlweeklychallenge.org/>
    =item2 L<Raku Advent Calendar|https://raku-advent.blog/>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>
    =item2 L<empty|#>

=end nested
=end React


=begin React :component<CookieConsent> :id<CookieConsent> :buttonCaption("Got it!")
=para
This website uses cookies for analytics.
=end React


ValueType

NAME

SYNOPSIS

DESCRIPTION

THEORY OF OPERATION

AUTHOR

COPYRIGHT AND LICENSE

ValueType v0.0.4

Authors

License

Dependencies

Test Dependencies

Provides

Documentation