NAME
Evo::Class
VERSION
version 0.0242
DESCRIPTION
INTRO
This module doesn't use perl's @ISA inheritance. This module isn't Moose compatible by design
Documentation will be available soon.
SYNOPSYS
package main;
use Evo;
{
package My::Human;
use Evo -Class, -Loaded;
has 'name' => 'unnamed';
has 'gender', is => 'ro', required => 1;
has age => check => sub($v) { $v >= 18 };
sub greet($self) { say "I'm " . $self->name }
}
my $alex = My::Human->new(gender => 'male');
# default value "unnamed"
say $alex->name;
# fluent design
$alex->name('Alex')->age(18);
say $alex->name, ': ', $alex->age;
# method
$alex->greet;
## ------------ protecting you from errors, uncomment to test
## will die, gender is required
#My::Human->new();
## will die, age must be >= 18
#My::Human->new(age => 17, gender => 'male');
#My::Human->new(gender => 'male')->age(17);
# --------- code reuse
{
package My::Developer;
use Evo -Class;
with 'My::Human'; # extends 'My::Human'; implements 'My::Human';
has lang => 'Perl';
sub show($self) {
$self->greet();
say "I like ", $self->lang;
}
}
my $dev = My::Developer->new(gender => 'male');
$dev->show;Usage
creating an object
package My::Class;
use Evo -Class;
has 'simple';new
my $foo = My::Class->new(simple => 1);
my $foo2 = My::Class->new();We're protected from common mistakes, because constructor won't accept unknown attributes.
Declaring attribute
package My::Foo;
use Evo '-Class *';
has 'simple';
has 'short' => 'value';
has 'foo' => default => 'value', is => 'rw', check => sub {1};Syntax
Simple rw attribute
has 'simple';
# has 'simple', is => 'rw';Attribute with default value: short form
has 'short' => 'value';
# has 'short', default => 'value';Full form
has 'foo' => default => 'value', is => 'rw', check => sub {1};Options
is
Can be 'rw' or 'ro'; Unlike Perl6 is 'rw' by default
default
Attribute will be filled with this value if isn't provided to the new constructor You can't use references, but you can provide a coderef instead of value, in this case return value of an invocation of this function will be used.
has ref => sub($class) { {} };
has foo => default => sub($class) { [] };This is a good way to init some attribute that should always exists. Arguments, passed to new or init will be passed to the function without object itself (because there are no object yet). If you're expecting another behaviour, check "lazy"
lazy
Like default, but will be filled at the first invocation, not in constructor, and an instance will be passed as the argument
# pay attention, an instance is passed
has foo => lazy => sub($self) { [] };You should know that using this feature is an antipattern in the most of the cases. "default" is preferable if you're not sure
required
has 'foo', required => 1;Attributes with this options are required and will be checked in new and init, an exception will be thrown if required attributes don't exist in arguments hash.
has 'db', required => 'My::DB';You can also pass any TRUE value for storing in the "META" of the class.
TODO: describe how to use it with dependency injection
check
You can provide function that will check passed value (via constuctor and changing), and if that function doesn't return true, an exception will be thrown.
has big => check => sub { shift > 10 };You can also return (0, "CustomError") to provide more expressive explanation
package main;
use Evo;
{
package My::Foo;
use Evo '-Class *';
has big => check => sub($val) { $val > 10 ? 1 : (0, "not > 10"); };
};
my $foo = My::Foo->new(big => 11);
$foo->big(9); # will die
my $bar = My::Foo->new(big => 9); # will dieCODE REUSE
All methods, defined in a class (not imported) are public. Functions, imported from other modules, don't become public and don't make a mess.
All attributes are public.
Methods, generated somehow else, for example by *foo = sub {}, can be marked as public by "reg_method" in Evo::Class::Meta
Private methods
If you want to mark a method as private, use new lexical_subs feature
my sub private {'private'}You can also use "mark_as_private" in Evo::Class::Meta
Overriding
Evo protects you from method clashing. But if you want to override method or fix clashing, use "has_over" function or :Override attribute
package My::Peter;
use Evo -Class;
with 'My::Human';
has_over name => 'peter';
sub greet : Over { }This differs from traditional OO style. With compoment programming, you should reuse code via Evo::Class::Role or just organize classes with independed pieces of code like "mixing". So, try to override less
FUNCTIONS
This functions will be exported by default even without export list use Evo::Class; You can always export something else like use Evo::Class 'has'; or export nothing use Evo::Class ();
META
Return current Evo::Class::Meta object for the class.
use Data::Dumper;
say Dumper __PACKAGE__->META->info;See what's going on with the help of "info" in Evo::Class::Meta
extends
Extends classes or roles
implements
Check if all required methods are implemented. Like interfaces
with
This does "extend + check implementation". Consider this example:
package main;
use Evo;
{
package My::Role::Happy;
use Evo -Class, -Loaded;
requires 'name';
sub greet($self) {
say "My name is ", $self->name, " and I'm happy!";
}
package My::Class;
use Evo -Class;
has name => 'alex';
#extends 'My::Role::Happy';
#implements 'My::Role::Happy';
with 'My::Role::Happy';
}
My::Class->new()->greet();My::Role::Happy requires name in derivered class. We could install shared code with extends and then check implemantation with implements. Or just use with wich does both.
You may want to use extends and implements separately to resolve circular requirements, for example
CODE ATTRIBUTES
sub foo : Over { 'OVERRIDEN'; }Mark name as overridden. See "Overriding methods" in Evo::Role
AUTHOR
alexbyk.com
COPYRIGHT AND LICENSE
This software is copyright (c) 2016 by alexbyk.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.