NAME

Venus::Role::Coercible - Coercible Role

ABSTRACT

Coercible Role for Perl 5

SYNOPSIS

package Person;

use Venus::Class;

with 'Venus::Role::Coercible';

attr 'name';
attr 'father';
attr 'mother';
attr 'siblings';

sub coercers {
  {
    father => 'Person',
    mother => 'Person',
    name => 'Venus/String',
    siblings => 'Person',
  }
}

sub coerce_name {
  my ($self, $code, @args) = @_;

  return $self->$code(@args);
}

sub coerce_siblings {
  my ($self, $code, $class, $value) = @_;

  return [map $self->$code($class, $_), @$value];
}

package main;

my $person = Person->new(
  name => 'me',
  father => {name => 'father'},
  mother => {name => 'mother'},
  siblings => [{name => 'brother'}, {name => 'sister'}],
);

# $person
# bless({...}, 'Person')

# $person->name
# bless({...}, 'Venus::String')

# $person->father
# bless({...}, 'Person')

# $person->mother
# bless({...}, 'Person')

# $person->siblings
# [bless({...}, 'Person'), bless({...}, 'Person'), ...]

DESCRIPTION

This package modifies the consuming package and provides methods for hooking into object construction and coercing arguments into objects and values.

METHODS

This package provides the following methods:

coerce_args

coerce_args(HashRef $data, HashRef $spec) (HashRef)

The coerce_args method replaces values in the data provided with objects corresponding to the specification provided. The specification should contains key/value pairs where the keys map to class attributes (or input parameters) and the values are Venus::Space compatible package names.

Since 0.07

coerce_args example 1

package main;

my $person = Person->new;

my $data = $person->coerce_args(
  {
    father => { name => 'father' }
  },
  {
    father => 'Person',
  },
);

# {
#   father   => bless({...}, 'Person'),
# }

coerce_attr

coerce_attr(Str $name, Any $value) (Any)

The coerce_attr method is a surrogate accessor and gets and/or sets an instance attribute based on the coercion rules, returning the coerced value.

Since 1.23

coerce_attr example 1

# given: synopsis

package main;

$person = Person->new(
  name => 'me',
);

my $coerce_name = $person->coerce_attr('name');

# bless({value => "me"}, "Venus::String")

coerce_attr example 2

# given: synopsis

package main;

$person = Person->new(
  name => 'me',
);

my $coerce_name = $person->coerce_attr('name', 'myself');

# bless({value => "myself"}, "Venus::String")

coerce_into

coerce_into(Str $class, Any $value) (Object)

The coerce_into method attempts to build and return an object based on the class name and value provided, unless the value provided is already an object derived from the specified class.

Since 0.07

coerce_into example 1

package main;

my $person = Person->new;

my $friend = $person->coerce_into('Person', {
  name => 'friend',
});

# bless({...}, 'Person')

coerce_onto

coerce_onto(HashRef $data, Str $name, Str $class, Any $value) (Object)

The coerce_onto method attempts to build and assign an object based on the class name and value provided, as the value corresponding to the name specified, in the data provided. If the $value is omitted, the value corresponding to the name in the $data will be used.

Since 0.07

coerce_onto example 1

package main;

my $person = Person->new;

my $data = { friend => { name => 'friend' } };

my $friend = $person->coerce_onto($data, 'friend', 'Person');

# bless({...}, 'Person'),

# $data was updated
#
# {
#   friend => bless({...}, 'Person'),
# }

coerce_onto example 2

package Player;

use Venus::Class;

with 'Venus::Role::Coercible';

attr 'name';
attr 'teammates';

sub coercers {
  {
    teammates => 'Person',
  }
}

sub coerce_into_person {
  my ($self, $class, $value) = @_;

  return $class->new($value);
}

sub coerce_into_venus_string {
  my ($self, $class, $value) = @_;

  return $class->new($value);
}

sub coerce_teammates {
  my ($self, $code, $class, $value) = @_;

  return [map $self->$code($class, $_), @$value];
}

package main;

my $player = Player->new;

my $data = { teammates => [{ name => 'player2' }, { name => 'player3' }] };

my $teammates = $player->coerce_onto($data, 'teammates', 'Person');

# [bless({...}, 'Person'), bless({...}, 'Person')]

# $data was updated
#
# {
#   teammates => [bless({...}, 'Person'), bless({...}, 'Person')],
# }

coercers

coercers() (HashRef)

The coercers method, if defined, is called during object construction, or by the "coercion" method, and returns key/value pairs where the keys map to class attributes (or input parameters) and the values are Venus::Space compatible package names.

Since 0.02

coercers example 1

package main;

my $person = Person->new(
  name => 'me',
);

my $coercers = $person->coercers;

# {
#   father   => "Person",
#   mother   => "Person",
#   name     => "Venus/String",
#   siblings => "Person",
# }

coercion

coercion(HashRef $data) (HashRef)

The coercion method is called automatically during object construction but can be called manually as well, and is passed a hashref to coerce and return.

Since 0.02

coercion example 1

package main;

my $person = Person->new;

my $coercion = $person->coercion({
  name => 'me',
});

# $coercion
# {...}

# $coercion->{name}
# bless({...}, 'Venus::String')

# $coercion->{father}
# undef

# $coercion->{mother}
# undef

# $coercion->{siblings}
# undef

coercion example 2

package main;

my $person = Person->new;

my $coercion = $person->coercion({
  name => 'me',
  mother => {name => 'mother'},
  siblings => [{name => 'brother'}, {name => 'sister'}],
});

# $coercion
# {...}

# $coercion->{name}
# bless({...}, 'Venus::String')

# $coercion->{father}
# undef

# $coercion->{mother}
# bless({...}, 'Person')

# $coercion->{siblings}
# [bless({...}, 'Person'), bless({...}, 'Person'), ...]

cpanm Venus

perl -MCPAN -e shell
install Venus