Error executing cascade class methods

Question

I have the following code:

1.  $customer = new Customer($apiContext);
2.  $customer->setVat('XYZ0123456')
3.           ->setName('Filipe')
4.           ->setLanguageId(1);
5.  (...)

The following error occurs on line 3:

Call to a Member Function setName() on a non-object

It is not possible to call cascading methods of the same class as shown above?

Answer 1

To execute the code this way (Method Chaining) it is necessary that your class Customer implement a standard called Fluent Interface^en.

To be able to do this in PHP it is necessary that the methods of your class to be chained return the instance of itself ($this).

Your class will look like this:

<?php

class Customer {

    public function setVat($vat){
        // ....     
        return $this;
    }

    public function setName($name){
        // ...      
        return $this;
    }

    public function setLanguageId($languageId){
        // ...      
        return $this;
    }

    // ...

}

Another way to do this with PHP is by using the magic method __call() together with private setters.

<?php

class Customer {

    private function setVat($vat){
        // ....     
    }

    private function setName($name){
        // ...      
    }

    public function __call($name, $arguments){
        if (method_exists($this, $name) && strpos($name, 'set') === 0) 
        {
            $this->$name($arguments[0]);   // Tratar o número de argumentos passados é 
                                           // uma boa ideia

            //$this->$name(...$arguments); // A partir do PHP 5.6
            return $this;
        } 
        else 
        {
            throw new Exception('Invalid setter method');
        }
    }
    // ...
}

The public methods of the class would be accessed perfectly, only the setters that are private and are not exposed outside the classes that would enter the __call(). Forcing all setters to go through __call() we don’t need to define the return of $this in all methods.

The strpos($name, 'set') === 0 protects the private methods of our class that do not begin with set, thus preventing undue access to private class methods.

Answer 2

So you can create "method chaining", your methods need to resume $this, that is to say:

class Customer {
    function setVat() {
      echo "bubu!";
      return $this;
    }

    function setName() {
       echo "Bubu2!";
       return $this;
    }
}

And then you can:

$Customer = new Customer;
$Customer->setVat()->setName();