php5中Iterator與smarty整合 – 馬永占 譯

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php5中Iterator與smarty整合

Iterator(迭代器)在PHP5中是非常重要的，我注意到Iterator在Smarty中不能正常的工作。
Smarty會自動將一個object(對象)轉換成array(數組)，所以當年在Smarty中迴圈輸出一個object時，模板會自動迴圈這個object的屬性。
例如，建立一個類，然後在函數中定義某些要迴圈的部分，將這些部分放到protected類型的$_data變數中。
<?php
    class MyClass implements Iterator
    {
        protected $_data = array();
 
        public function rewind()
        {
            reset($this->_data);
        }
 
        public function current()
        {
            return current($this->_data);
        }
 
        public function key()
        {
            return key($this->_data);
        }
 
        public function next()
        {
            return next($this->_data);
        }
 
        public function valid()
        {
            return $this->current() !== false;
        }
 
        public function size()
        {
            return count($this->_data);
        }
    }
?>
然後在Smarty使用這個類
{foreach from=$myClassObj item=row}
    {$row}
{/foreach}
這樣不會輸出想要的結果，下面做一下簡單的修改，將$myClassObj改成$myClassObj->getData()：
{foreach from=$myClassObj->getData() item=row}
    {$row}
{/foreach}
這樣就能輸出正確的結果了。

 

 

phpRiot.com: Using the PHP 5 Iterator interface with Smarty

The PHP 5 Iterator interface is very useful for defining custom behaviour for looping over objects, however I just noticed that looping over such objects in Smarty will not work correctly.

Smarty will in fact cast an object back to an array, so when you loop over it, the template will loop over the object's properties (as opposed to using the rules defined by the Iterator methods).

For example, I used code similar to the following to create a class over which I can loop. This lets me loop over the protected $_data array.

<?php
    class MyClass implements Iterator
    {
        protected $_data = array();
 
        public function rewind()
        {
            reset($this->_data);
        }
 
        public function current()
        {
            return current($this->_data);
        }
 
        public function key()
        {
            return key($this->_data);
        }
 
        public function next()
        {
            return next($this->_data);
        }
 
        public function valid()
        {
            return $this->current() !== false;
        }
 
        public function size()
        {
            return count($this->_data);
        }
    }
?>

What I want to be able to do is loop over each element in the array with the following code:

{foreach from=$myClassObj item=row}
    {$row}
{/foreach}

However, this will not work as expected in Smarty. To get around, I implemented as method called getData() which simply returned the array. This meant my template had to look as follows:

{foreach from=$myClassObj->getData() item=row}
    {$row}
{/foreach}

It's a bit annoying to have to do this, since in some ways it defeats the purpose of the using the Iterator interface, but I guess sometimes small sacrifices need to be made.