mangelsnc/specific-class-collection

Abstract class to build Specific Type Collection classes

, _(*1)

SpecificClassCollection

Installation

Just execute:, _(*2)

composer require mangelsnc/specific-class-collection

Description

This abstract class allows you to create collections of a specific class., _(*3)

Have you ever seen something like this in Java?, _(*4)

public String join (ArrayList<String> collection) {
    String joinedString = '';

    for (String temp : collection) {
        joinedString.concat(temp);
    }

    return joinedString;
}

It's very useful to have a collection that ensures all the objects contained on it are of some specific class., _(*5)

PHP lacks of something like that, and we are forced to make unelegant code like this:, _(*6)

<?php

namespace Solid\ApplicationService;

use Solid\ApplicationService\ValidatorRules\IdentityNumberValidatorRuleInterface;

class IdentityNumberValidator
{
    private $validators;

    public function __construct($validators = [])
    {
        foreach ($validators as $validator) {
            if ($validator instanceof IdentityNumberValidatorRuleInterface) {
                $this->validators[$validator->getClassName()] = $validator;
            }
        }
    }

    // more code
}

In this case we want to pass to the constructor a collection of validators, but there's no an easy way to do it in PHP, so, we perform a validation of the type in the same constructor., _(*7)

This is not elegant, but moreover, it can make these validator not work if there's no item implementing the desired interface in the array passed to the constructor., _(*8)

With collections, the old constructor can be refactored as this:, _(*9)

<?php

namespace Solid\ApplicationService;

use Solid\ApplicationService\ValidatorRules\IdentityNumberValidatorRuleCollection;
use Solid\ApplicationService\ValidatorRules\IdentityNumberValidatorRuleInterface;

class IdentityNumberValidator
{
    private $validators;

    public function __construct(IdentityNumberValidatorRuleCollection $validators)
    {
        foreach ($validators as $validator) {
            $this->validators[$validator->getClassName()] = $validator;
        }
    }

    // more code
}

Leaving a clean constructor and delegating the validation of the types to the correct place., _(*10)

Note: The collections can be iterated as an array or if you prefer, you can call the method getElements the get the array., _(*11)

Create a collection class

With this little helper, create a specific collection class is easy as this:, _(*12)

<?php

namespace Solid\ApplicationService\ValidatorRules;

use SpecificClassCollection\SpecificClassCollection;
use Solid\ApplicationService\ValidatorRules\IdentityNumberValidatorRuleInterface;

class IdentityNumberValidatorRuleCollection extends SpecificClassCollection
{

    protected function getValidClassName()
    {
        return IdentityNumberValidatorRuleInterface::class;
    }
}

Manipulate the collection

Add elements to a collection:, _(*13)

$collection = new IdentityNumberValidatorRuleCollection();
$collection->add($rule);
$collection->add($rule);

Get the number of elements inside the collection:, _(*14)

$collection->count();

Reset the collection content:, _(*15)

$collection->clear();