PHP方法链接?

我正在使用PHP 5,并且我听说过面向对象方法中的一个新特性,称为“方法链”。究竟是什么?我该如何实现它?     
已邀请:
它非常简单,你有一系列mutator方法都返回原始(或其他)对象,这样你就可以继续调用返回对象的方法。
<?php
class fakeString
{
    private $str;
    function __construct()
    {
        $this->str = "";
    }

    function addA()
    {
        $this->str .= "a";
        return $this;
    }

    function addB()
    {
        $this->str .= "b";
        return $this;
    }

    function getStr()
    {
        return $this->str;
    }
}


$a = new fakeString();


echo $a->addA()->addB()->getStr();
输出“ab” 在线尝试!     
基本上,你拿一个对象:
$obj = new ObjectWithChainableMethods();
调用最终有效地执行
return $this;
的方法:
$obj->doSomething();
由于它返回相同的对象,或者更确切地说是对同一对象的引用,因此可以继续从返回值中调用同一类的方法,如下所示:
$obj->doSomething()->doSomethingElse();
就是这样,真的。两件重要的事情: 如你所知,它只是PHP 5。它在PHP 4中无法正常工作,因为它按值返回对象,这意味着您在对象的不同副本上调用方法,这会破坏您的代码。 同样,您需要在可链接方法中返回对象:
public function doSomething() {
    // Do stuff
    return $this;
}

public function doSomethingElse() {
    // Do more stuff
    return $this;
}
    
试试这段代码:
<?php
class DBManager
{
    private $selectables = array();
    private $table;
    private $whereClause;
    private $limit;

    public function select() {
        $this->selectables = func_get_args();
        return $this;
    }

    public function from($table) {
        $this->table = $table;
        return $this;
    }

    public function where($where) {
        $this->whereClause = $where;
        return $this;
    }

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

    public function result() {
        $query[] = "SELECT";
        // if the selectables array is empty, select all
        if (empty($this->selectables)) {
            $query[] = "*";  
        }
        // else select according to selectables
        else {
            $query[] = join(', ', $this->selectables);
        }

        $query[] = "FROM";
        $query[] = $this->table;

        if (!empty($this->whereClause)) {
            $query[] = "WHERE";
            $query[] = $this->whereClause;
        }

        if (!empty($this->limit)) {
            $query[] = "LIMIT";
            $query[] = $this->limit;
        }

        return join(' ', $query);
    }
}

// Now to use the class and see how METHOD CHAINING works
// let us instantiate the class DBManager
$testOne = new DBManager();
$testOne->select()->from('users');
echo $testOne->result();
// OR
echo $testOne->select()->from('users')->result();
// both displays: 'SELECT * FROM users'

$testTwo = new DBManager();
$testTwo->select()->from('posts')->where('id > 200')->limit(10);
echo $testTwo->result();
// this displays: 'SELECT * FROM posts WHERE id > 200 LIMIT 10'

$testThree = new DBManager();
$testThree->select(
    'firstname',
    'email',
    'country',
    'city'
)->from('users')->where('id = 2399');
echo $testThree->result();
// this will display:
// 'SELECT firstname, email, country, city FROM users WHERE id = 2399'

?>
    
方法链接意味着您可以链接方法调用:
$object->method1()->method2()->method3()
这意味着method1()需要返回一个对象,而method2()则给出了method1()的结果。然后,Method2()将返回值传递给method3()。 好文章:http://www.talkphp.com/advanced-php-programming/1163-php5-method-chaining.html     
静态方法链接的另一种方法:
class Maker 
{
    private static $result      = null;
    private static $delimiter   = '.';
    private static $data        = [];

    public static function words($words)
    {
        if( !empty($words) && count($words) )
        {
            foreach ($words as $w)
            {
                self::$data[] = $w;
            }
        }        
        return new static;
    }

    public static function concate($delimiter)
    {
        self::$delimiter = $delimiter;
        foreach (self::$data as $d)
        {
            self::$result .= $d.$delimiter;
        }
        return new static;
    }

    public static function get()
    {
        return rtrim(self::$result, self::$delimiter);
    }    
}
调用
echo Maker::words(['foo', 'bob', 'bar'])->concate('-')->get();

echo "<br />";

echo Maker::words(['foo', 'bob', 'bar'])->concate('>')->get();
    
有49行代码允许您将方法链接到数组,如下所示:
$fruits = new Arr(array("lemon", "orange", "banana", "apple"));
$fruits->change_key_case(CASE_UPPER)->filter()->walk(function($value,$key) {
     echo $key.': '.$value."rn";
});
请参阅本文,其中介绍了如何链接所有PHP的70个array_函数。 http://domexception.blogspot.fi/2013/08/php-magic-methods-and-arrayobject.html     
如果你的意思是方法链接就像在JavaScript中(或者有些人记住jQuery),为什么不只是带一个带来该开发的库。 PHP的经验?例如Extras - https://dsheiko.github.io/extras/这个使用JavaScript和Underscore方法扩展PHP类型并提供链接: 您可以链接特定类型:
<?php
use DsheikoExtrasArrays;
// Chain of calls
$res = Arrays::chain([1, 2, 3])
    ->map(function($num){ return $num + 1; })
    ->filter(function($num){ return $num > 1; })
    ->reduce(function($carry, $num){ return $carry + $num; }, 0)
    ->value();
要么
<?php
use DsheikoExtrasStrings;
$res = Strings::from( " 12345 " )
            ->replace("/1/", "5")
            ->replace("/2/", "5")
            ->trim()
            ->substr(1, 3)
            ->get();
echo $res; // "534"
或者你可以去多态:
<?php
use DsheikoExtrasAny;

$res = Any::chain(new ArrayObject([1,2,3]))
    ->toArray() // value is [1,2,3]
    ->map(function($num){ return [ "num" => $num ]; })
    // value is [[ "num" => 1, ..]]
    ->reduce(function($carry, $arr){
        $carry .= $arr["num"];
        return $carry;

    }, "") // value is "123"
    ->replace("/2/", "") // value is "13"
    ->then(function($value){
      if (empty($value)) {
        throw new Exception("Empty value");
      }
      return $value;
    })
    ->value();
echo $res; // "13"
    
下面是我的模型,可以通过数据库中的ID找到。 with($ data)方法是我关系的附加参数,所以我返回$ this,它就是对象本身。在我的控制器上,我能够链接它。
class JobModel implements JobInterface{

        protected $job;

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

        public function find($id){
            return $this->job->find($id);
        }

        public function with($data=[]){
            $this->job = $this->job->with($params);
            return $this;
        }
}

class JobController{
    protected $job;

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

    public function index(){
        // chaining must be in order
        $this->job->with(['data'])->find(1);
    }
}
    

要回复问题请先登录注册