PHP OOP: Method Chaining

Question

I have the following code,

<?php
class Templater
{
    static $params = array();

    public static function assign($name, $value)
    {
        self::$params[] = array($name => $value);
    }

    public static function draw()
    {
        self::$params;
    }
}


 $test = Templater::assign('key', 'value');
 $test = Templater::draw();
 print_r($test);

How can I alter this script so I could use this?

$test = Templater::assign('key', 'value')->assign('key2', 'value2')->draw();
print_r($test);

You may also want to modify the assign() method so it can accept an array of key => values. — allnightgrocery
– allnightgrocery, Commented Jun 7, 2010 at 15:52
You should be more precise in what you really want to do. Does a simple associative array served your purpose? — mathk
– mathk, Commented Jun 7, 2010 at 15:55

Community · Accepted Answer · 2017-05-23 11:45:36Z

6

You cannot use Method Chaining with static methods because you cannot return a class level scope (return self won't do). Change your methods to regular methods and return $this in each method you want to allow chaining from.

Notice that you should not use T_PAAMAYIM_NEKUDOTAYIM to access instance methods as it will raise an E_STRICT Notice. Use T_OBJECT_OPERATOR for calling instance methods.

Also see:

Chaining Static Methods in PHP?

edited May 23, 2017 at 11:45

CommunityBot

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answered Jun 7, 2010 at 15:53

Gordon

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Comments

Diego Vieira · Accepted Answer · 2021-04-22 11:17:41Z

6

You shouldn't be using static members:

class Templater
{
    private array $params = [];

    public function assign($name, $value) : self
    {
        $this->params[$name] = $value;

        return $this;
    }

    public function draw()
    {
        // do something with $this->params
    }
}

$test = (new Templater())->assign('key', 'value')->assign('key2', 'value2')->draw();

edited Apr 22, 2021 at 11:17

Diego Vieira

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answered Jun 7, 2010 at 15:51

Artefacto

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1 Comment

Galen Over a year ago

you can't chain off of a constructor like that!

vartec · Accepted Answer · 2010-06-07 16:04:15Z

3

Just use instance variables and instance functions instead of static ones.

<?php
class Templater
{
    $params = array();

    public function assign($name, $value)
    {
        $this->params[] = array($name => $value); 
        return $this;
    }

    public function draw()
    {
        echo $this->params;
        return $this;
    }
}

$test = new Templater();
$test->assign('key', 'value')->assign('key2', 'value2')->draw();
print_r($test);

edited Jun 7, 2010 at 16:04

answered Jun 7, 2010 at 15:49

vartec

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1 Comment

Rich Adams Over a year ago

You need to add "return $this;" at the end of the assign() method otherwise the chaining won't work.

Akram Younes · Accepted Answer · 2014-09-25 03:32:20Z

1

////////

class Templater { static $params = array();

public static function assign($name, $value)
{
    self::$params[] = array($name => $value);
    return new Templater;
}

public static function draw()
{
    return self::$params;
}

}

$test = Templater::assign('key', 'value')->assign('key2', 'value2')->draw(); print_r($test);

answered Sep 25, 2014 at 3:32

Akram Younes

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1 Comment

mickmackusa Over a year ago

This answer is missing its educational explanation and proper formatting.

Joe Mastey · Accepted Answer · 2010-06-07 15:58:36Z

0

Mixing a static and an instance call like that is poor form in general, omitting that one (unless you give a reason that it needs to be static). The other concept you're working with is call chaining, which is implemented using returns.

class Templater
{
    protected $params = array();

    public function assign($name, $value) {
        $this->params[] = array($name => $value);
        return $this;
    }

    public function draw() {
        // do drawing w/ $this->params;
        return $this;
    }
}

answered Jun 7, 2010 at 15:58

Joe Mastey

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Comments

Isis · Accepted Answer · 2010-06-07 16:09:30Z

0

class Templater
{   
    public static $params;

    private static $_instance = null;

    public static function init()
    {
        if (self::$_instance === null)
        {
            self::$_instance = new self;
        }

        return self::$_instance;
    }

    public function assign($name, $value)
    {
        self::$params[$name] = $value;
        return $this;
    }

    public function draw()
    {
        return self::$params;
    }
}

$test = Templater::init()->assign('key', 'value')->assign('key2', 'value2')->draw();

answered Jun 7, 2010 at 16:09

Isis

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