CODEWITHSUNDEEP
phpoopgetter-setter
Peck3277
Peck3277

Reputation: 1423

Reduce the amount of getter and setter calls from class

This is probably a stupid question but I can't figure out what to google. I'm learning OOP and get the general concept but trying to implement it and I'm getting some questions.

I'm making a web scraper using simple html dom. I want to create a class which connects to a page and contains several different functions I can call on that page depending on what I want to do. I then can call this classes methods from another file.

This is the class I have written:

<?php

include_once '/simple_html_dom.php';

class CountyScraping
{
protected $demoMode = 0; //set 1 for demo
protected $cinemas = NULL;
protected $url = NULL;
protected $html = NULL;
protected $counties = array();

function __construct($url)
{
    $this->setUrl($url);
}

public function setUrl($url)
{
    $this->url = $url;
}

public function getUrl()
{
    return $this->url;
}

public function setHtml()
{
    $this->html = file_get_html($this->url);
}

public function getHtml()
{
    return $this->html;
}

public function setCounties()
{
    foreach($this->html->find('#UserLocation option') as $element)
    {
        if (($element->value != NULL) && ($element->plaintext))
        {   
            $county = array();
            $county['id'] = $element->value;
            $county['county_name'] = $element->plaintext;
            $this->counties[] = $county;
        }
    }
}

public function getCounties()
{
    return $this->counties;
}

?>

As you can see from the class above I'm looking to get a list of counties from my page and it's all working as should be. The main method I want to call is to get an array of counties. Using the code above to get a list of counties I have to do something like this currently:

$scrape = new CountyScraping("http://example.com");

$scrape->setHtml();
$scrape->setCounties();
$counties = $scrape->getCounties();

This works fine and I could continue with this however I feel like I'm making a lot of calls to getters and setters from outside the class. I think I should be making one call, getCounties and have everything be handled inside the class.

Am I correct in assuming this? Should my getCounties() method call my setHtml and setCounties methods? Or should I be keeping my getters and setters as minimal as possible and have another function instead?

Any advice about any part of my code would be welcome.

Upvotes: 0

Views: 366

Answers (2)

Gnucki
Gnucki

Reputation: 5133

I would suggest you to always use an SOA (service oriented architecture) when you want to develop with OOP. With SOA your service coming from the class CountyScraper should be unique. This is why we use a singleton. A service shouldn't keep a state from an action. This is why you shouldn't set the url or html as properties.

<?php

include_once '/simple_html_dom.php';

class CountyScraper
{
    /**
     * Returns the *Singleton* instance of this class.
     *
     * @staticvar Singleton $instance The *Singleton* instances of this class.
     *
     * @return Singleton The *Singleton* instance.
     */
    public static function getInstance()
    {
        static $instance = null;
        if (null === $instance) {
            $instance = new static();
        }

        return $instance;
    }

    /**
     * Protected constructor to prevent creating a new instance of the
     * *Singleton* via the `new` operator from outside of this class.
     */
    protected function __construct()
    {
    }

    /**
     * Private clone method to prevent cloning of the instance of the
     * *Singleton* instance.
     *
     * @return void
     */
    private function __clone()
    {
    }

    /**
     * Private unserialize method to prevent unserializing of the *Singleton*
     * instance.
     *
     * @return void
     */
    private function __wakeup()
    {
    }

    public function findCounties($url)
    {
        $counties = array();
        $html = file_get_html($url);

        foreach ($html->find('#UserLocation option') as $element)
        {
            if (($element->value != NULL) && ($element->plaintext))
            {   
                $county = array();
                $county['id'] = $element->value;
                $county['county_name'] = $element->plaintext;
                $counties[] = $county;
            }
        }
    }
}

Then, you can use it like that:

$countyScraper = CountyScraper::getInstance();

$countyScraper->findCounties('http://example.com');

Upvotes: 0

clonelab
clonelab

Reputation: 651

PHP magic methods will help you a bit more also. Here is a link to the php manual for __set() http://php.net/manual/en/language.oop5.overloading.php#object.set

here is also a nice articale that will assist you with more information on magic methods http://culttt.com/2014/04/16/php-magic-methods/

Here is a basic example of magic methods

<?php
class PropertyTest
{
    /**  Location for overloaded data.  */
    private $data = array();

    /**  Overloading not used on declared properties.  */
    public $declared = 1;

    /**  Overloading only used on this when accessed outside the class.  */
    private $hidden = 2;

    public function __set($name, $value)
    {
        echo "Setting '$name' to '$value'\n";
        $this->data[$name] = $value;
    }

    public function __get($name)
    {
        echo "Getting '$name'\n";
        if (array_key_exists($name, $this->data)) {
            return $this->data[$name];
        }

        $trace = debug_backtrace();
        trigger_error(
            'Undefined property via __get(): ' . $name .
            ' in ' . $trace[0]['file'] .
            ' on line ' . $trace[0]['line'],
            E_USER_NOTICE);
        return null;
    }

    /**  As of PHP 5.1.0  */
    public function __isset($name)
    {
        echo "Is '$name' set?\n";
        return isset($this->data[$name]);
    }

    /**  As of PHP 5.1.0  */
    public function __unset($name)
    {
        echo "Unsetting '$name'\n";
        unset($this->data[$name]);
    }

    /**  Not a magic method, just here for example.  */
    public function getHidden()
    {
        return $this->hidden;
    }
}


echo "<pre>\n";

$obj = new PropertyTest;

$obj->a = 1;
echo $obj->a . "\n\n";

var_dump(isset($obj->a));
unset($obj->a);
var_dump(isset($obj->a));
echo "\n";

echo $obj->declared . "\n\n";

echo "Let's experiment with the private property named 'hidden':\n";
echo "Privates are visible inside the class, so __get() not used...\n";
echo $obj->getHidden() . "\n";
echo "Privates not visible outside of class, so __get() is used...\n";
echo $obj->hidden . "\n";
?>

Output is here:

Setting 'a' to '1'
Getting 'a'
1

Is 'a' set?
bool(true)
Unsetting 'a'
Is 'a' set?
bool(false)

1

Let's experiment with the private property named 'hidden':
Privates are visible inside the class, so __get() not used...
2
Privates not visible outside of class, so __get() is used...
Getting 'hidden'


Notice:  Undefined property via __get(): hidden in <file> on line 70 in <file> on line 29

This example has been sourced from http://php.net/manual/en/language.oop5.overloading.php#object.set

Upvotes: 2

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