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Anonymous 25-May-2011 11:06


The keyword 'use' has two different applications, but the reserved word table links to here.



It can apply to namespace constucts:



file1:

<?php namespace foo;

  class Cat { 

    static function says() {echo 'meoow';}  } ?>



file2:

<?php namespace bar;

  class Dog {

    static function says() {echo 'ruff';}  } ?>



file3:

<?php namespace animate;

  class Animal {

    static function breathes() {echo 'air';}  } ?>



file4:

<?php namespace fub;

  include 'file1.php';

  include 'file2.php';

  include 'file3.php';

  use foo as feline;

  use bar as canine;

  use animate;

  echo \feline\Cat::says(), "<br />\n";

  echo \canine\Dog::says(), "<br />\n";

  echo \animate\Animal::breathes(), "<br />\n";  ?>



Note that 

felineCat::says()

should be

\feline\Cat::says()

(and similar for the others)

but this comment form deletes the backslash (why???) 



The 'use' keyword also applies to closure constructs:



<?php function getTotal($products_costs, $tax)

    {

        $total = 0.00;

        

        $callback =

            function ($pricePerItem) use ($tax, &$total)

            {

                

                $total += $pricePerItem * ($tax + 1.0);

            };

        

        array_walk($products_costs, $callback);

        return round($total, 2);

    }

?>

netmosfera at gmail dot com 21-Apr-2011 11:09


for example, if you use a lot of .php files (once per class) you need to know that require() a lot of files will slow down consistently the page load



so you can use namespaces + autoload to implement package-specific initialization handlers



i used this to put an entire package (lot of classes) in one php file



!!! please note you can't use this as-is but you need to adapt it to your project



the file __init.php is placed inside every namespace/folder you want to load

there you can startup your namespace, check for environment, debugging, or as i do, you can merge all the package in one php file and require it to load other classes too.



<?php



class Loader

{

    // here we store the already-initialized namespaces

    private static $loadedNamespaces = array();

  

    static function loadClass($className)

    {

        // we assume the class AAA\BBB\CCC is placed in /AAA/BBB/CCC.php

        $className = str_replace(array('/', '\\'), \DIRECTORY_SEPARATOR, $className);

       

        // we get the namespace parts

        $namespaces = explode(\DIRECTORY_SEPARATOR, $className);

        unset($namespaces[sizeof($namespaces)-1]); // the last item is the classname

       

        // now we loops over namespaces

        $current=""; foreach($namespaces as $namepart)

        {

            // we chain $namepart to parent namespace string

            $current.='\\' . $namepart;

            // skip if the namespace is already initialized

            if(in_array($current, self::$loadedNamespaces)) continue;

            // wow, we got a namespace to load, so:

            $fnload = $current . \DIRECTORY_SEPARATOR . "__init.php";

            if(file_exists($fnload)) require($fnload);

            // then we flag the namespace as already-loaded

            self::$loadedNamespaces[] = $current;

        }



        // we build the filename to require

        $load = $className . ".php";

        // check for file existence

        !file_exists($load) ?: require($load);

        // return true if class is loaded

        return class_exists($className, false);

    }

    static function register()

    {

        spl_autoload_register("Loader::loadClass");

    }

    static function unregister()

    {

        spl_autoload_unregister("Loader::loadClass");

    }

}



Loader::register();



?>

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