php - PHP 中的类方法

Question

我来自 Ruby 世界，我目前正在从事一个 PHP 项目。

就像在 Ruby 脚本中一样，是否可以在 PHP 中声明类方法？基本上，我在问 PHP 中以下代码的等价物是什么

class A
  def hello; "hello from object"; end
  def self.hello; "hello from class"; end
end

注意实例方法和类方法的区别。

Answer 1

class A
  def hello; "hello from object"; end
  def self.hello; "hello from class"; end
end

class A {
    // attributes or properties
    public $age; 
    private $gender; 
    protected $location; 
    // needs to be static to be called as self:: inside the class
    public static function hello(){
         return "hello from object";
    }
    // use this keyword to be called inside the class
    public function hello1(){
        return "hello from object";
    }
    public function hello2(){
         print(self::hello());
         print(this->hello1());
    }
    // How about private method
    private function hello3(){
         return "hello world";
    }
}

Calling Outside the class

$instance = new A();
//static
$instance::hello();
//non static
$instance->hello1();
$instance->hello2();

Answer 2

在 PHP 中，类方法通常被称为静态方法并被声明为静态方法。直接翻译你的例子： -

class A
{
    public function hello()
    {
        return "hello from object";
    }

    //We can't have two methods with the same name.
    public static function s_hello()
    {
        return "hello from class";
    }
}

然后你会调用这样的方法： -

//For a static method we don't need an instance
echo A::s_hello;
//But we do for an instance method
$a = new A();
echo $a->hello();

你也可以有静态属性，所以上面的例子可以这样修改：-

class A
{
    private static $s_hello = "hello from class";
    private $hello = "hello from object";

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

    //We can't have two methods with the same name.
    public static function s_hello()
    {
        return self::$hello;
    }
}

http://php.net/manual/en/language.oop5.static.php

Answer 3

看静态方法： http: //php.net/static

静态方法是这样调用的：

Foo::aStaticMethod();

Answer 4

php 中没有办法在单个类中对同一个函数进行多个定义

而你可以这样做

abstract class A{
 static function hello()
 {
   return 'hello';
 }
}

class B extends class A  
{
  function hello()
  {
  return 'hello from Object';
  }
}

A::hello();
$t = new B();
$t->hello();