class animal{
    PRivate $name;

    // TradITional setters and getters
    public function setName($name){
        $this->name = $name;
    }

    public function getName(){
        return $this->name;
    }

    // animal constructors
    function __construct(){
       // some code here
    }

    // vs

    function __construct($name){
        $this->name = $name;
        echo $this->name;
    }
}

$dog = new animal();
$dog->setName("spot");
echo $dog->getName();

// vs

$dog = new animal("spot");

这更像是语义问题,而不是每种说法的最佳实践.

在您的示例中,您的商务逻辑可能会确定动物总是需要一个名字.
因此,使用名称构造对象是有意义的.如果你不想允许
要改变动物的名字,那么你就不要写一个二传手.

即

class Animal 
{
    private $name;

    public function __construct($name)
    {
        $this->name = $name;
    }

    public function getName()
    {
        return $this->name;
    }
}

您可能拥有动物不必拥有的其他属性,例如所有者
你只写了一个getter / setter

class Animal
{
    private $name;
    private $owner;

    public function __construct($name)
    {    
        $this->name = $name;
    }

    public function getName()
    {
        return $this->name;
    }

    public function setOwner($owner)
    {
        $this->owner = $owner
    }
}

但是如果你发现你总是在同一时间与主人一起创造一种动物
为方便起见,您可能希望将其放在构造函数签名中

class Animal
{
    private $name;
    private $owner;

    public function __construct($name,$owner = null)
    {    
        $this->name = $name;
        $this->owner = $owner;
    }

    public function getName()
    {
        return $this->name;
    }

    public function setOwner(Owner $owner)
    {
        $this->owner = $owner
    }

    public function getOwner()
    {
        return $this->owner;
    }
}

如果所有者是应用程序中的另一个类,则可以键入提示您的构造函数
需要特定类型(类)的所有者.所有这些都用于使您或其他开发人员更容易理解代码背后的一些要求/逻辑 – 以及可能在此处或那里捕获错误

class Owner 
{
    private $name;

    public function __construct($name)
    {    
        $this->name = $name;
    }
}

class Animal
{
    private $name;
    private $owner;

    public function __construct($name,Owner $owner = null)
    {    
        $this->name = $name;
        $this->owner = $owner;
    }

    public function getName()
    {
        return $this->name;
    }

    public function setOwner(Owner $owner)
    {
        $this->owner = $owner
    }

    public function getOwner()
    {
        return $this->owner;
    }
}

// Create a new owner!
$dave = new Owner('Farmer Dave');

// a standard PHP empty object
$otherObj = new \stdClass();

// Create a new animal
$daisy = new Animal('Daisy');

// Farmer dave owns Daisy
$daisy->setOwner($dave);

// Throws an error,because this isn't an instance of Owner
$daisy->setOwner($otherObj);

// Set up Maude,with Dave as the owner,a bit less code than before!
$maude = new Animal('Maude',$dave);