How to use PHP SPL and its power_PHP tutorial-PHP Tutorial-php.cn

How to use PHP SPL and its power_PHP tutorial

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Release： 2016-07-13 10:25:17

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SPL, PHP Standard Library (Standard PHP Library), is a built-in component and interface starting from PHP 5.0, and has gradually matured since PHP5.3. SPL is actually built into all PHP5 development environments and requires no setup.
It seems that many PHP developers basically don’t use it, or even heard of it. The reason can be traced back to its snow-like documentation, which makes you ignore "its existence". SPL This gem is like Titanic's "Heart of the Ocean", which was sunk to the bottom of the sea. Now it should be picked up by us and worn in its rightful place, and this is the point of view expressed in this article.
So, what does SPL offer?
SPL provides extensions to the PHP engine with interfaces such as ArrayAccess, Countable, and SeekableIterator, which are used to manipulate objects in the form of arrays. At the same time, you can also use other iterators such as RecursiveIterator and ArrayObjects to iterate data.
It also has several built-in objects such as Exceptions, SplObserver, Spltorage and helper functions such as splautoloadregister, splclasses, iteratorapply, etc., for overloading the corresponding functions.
These tools together are like a multifunctional Swiss Army knife. Making good use of them can qualitatively improve PHP code efficiency. So, how do we unleash its power?
Overloading autoloader
If you are a "textbook programmer", then you are guaranteed to know how to use __autoload to replace the includes/requires operation to lazily load the corresponding class, right?
But over time, you will find that you have fallen into trouble. First, you must ensure that your class files must be in the specified file path. For example, in the Zend framework, you must use "_" to separate class and method names ( How do you solve this problem? ).
Another problem is that as the project becomes more and more complex, the logic within __autoload will also become correspondingly complex. In the end, you will even add exception judgment and write all the logic of loading classes into it.
Everyone knows that "eggs cannot be put in one basket", and SPL can be used to separate the loading logic of __autoload. Just write your own autoload function and overload it using the functions provided by SPL.
For example, in the Zend framework problem mentioned above, you can overload the corresponding method of Zend loader. If it does not find the corresponding class, then it will use the function you defined previously.

Copy code The code is as follows:

class MyLoader {
public static function doAutoload( $class) {
// Autoload operation corresponding to this module
}
}

spl_autoload_register( array('MyLoader', 'doAutoload') );
?>

As you can see, spl autoload register can also add multiple loads in the form of an array Enter logic. At the same time, you can also use spl autoload unregister to remove loading logic that is no longer needed. This feature will always be used.
Iterator
Iteration is one of the common design patterns and is commonly used for unified traversal operations in a set of data. It is no exaggeration to say that SPL provides all the iterators you need for the corresponding data types.
A very good example is traversing directories. The conventional approach is to use scandir and then skip "." and "..", as well as other files that do not meet the conditions. For example, if you need to traverse a directory to extract image files, you need to determine whether they end in jpg or gif.
The following code is an example of using the SPL iterator to perform the above recursive search for image files in the specified directory:

Copy the code The code is as follows:

class RecursiveFileFilterIterator extends FilterIterator {
// Extension that meets the conditions
protected $ext = array('jpg','gif');
/ **
* Provide $path and generate the corresponding directory iterator
*/
public function __construct($path) {
parent::__construct(new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path)));
}
/**
* Check whether the file extension meets the conditions
*/
public function accept() {
$item = $this->getInnerIterator();
if ($item->isFile() &&
in_array(pathinfo($item ->getFilename(), PATHINFO_EXTENSION), $this->ext)) {
return TRUE; RecursiveFileFilterIterator('/path/to/something') as $item) {
echo $item . PHP_EOL;
}
?>

You might say, this Doesn’t it take more code to do the same thing? So, look at the above code, don’t you have a highly reusable and testable code? :)

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