在另一个方法中调用方法是一个好习惯吗？ - PHP

I would like to know if it's recommended to do this:

class User {

    public function __construct() {
        parent::__construct();
    }
    public function exists($token) {
        //return true if token exists otherwise return false
    }
    public function createSession($token) {
        if($this->exists($token))
            //create session
        else
            //redirect
    }
}

I think it could be not recommended in case of a change in the exists method of the class but I think that'll not happen, What do you recommend me to do?

There's nothing wrong with calling methods from other methods. In many designs, it's critical that you do this. This allows you to create subclasses that redefine the method, and the new definition will be called.

So if you do:

class SpecialUser extends User {
    public function exists($token) {
        // determine token existence in some other way
    }
}

You can then do:

$s = new SpecialUser;
$s->createSession($someToken);

and it will make use of the special way that SpecialUser checks tokens.

I do that all the time, when i notice my method is too long i segregate it and create another private method or protected method. Another reason is so it could be reuse for another method.

Here's an example:

class Download extends PHPExcel{

    public function excel2007()
    {
        $excelFormat = $this->excelFormat();
    }

    public function excel2003()
    {
        $excelFormat = $this->excelFormat();
    }

    private function excelFormat()
    {
        return [

            'font_bold' => [

                'font' => array(
                    'bold' => true
                )

            ],
            'font_size' => [

                'font' => array(
                    'size' => 10
                )   

            ],
            'align_center' => [

                'alignment' => array('horizontal' => PHPExcel_Style_Alignment::HORIZONTAL_CENTER)    

            ]
        ];
    }
}