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);
}
?>
Tested on PHP 7.0.5, Windows
The line "use animate;" equals the line "use animate as animate;"
but the "use other\animate;" equals "use other\animate as animate;"
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 other\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 other\animate; //use other\animate as animate;
echo feline\Cat::says(), "<br />\n";
echo canine\Dog::says(), "<br />\n";
echo \animate\Animal::breathes(), "<br />\n"; ?>
In addition to using namespaces and closures, the use keyword has another new meaning as of PHP 5.4 - using traits:
<?php
trait Hello {
public function sayHello() {
echo 'Hello ';
}
}
trait World {
public function sayWorld() {
echo 'World';
}
}
class MyHelloWorld {
use Hello, World;
public function sayExclamationMark() {
echo '!';
}
}
$o = new MyHelloWorld();
$o->sayHello();
$o->sayWorld();
$o->sayExclamationMark();
?>
More info here: http://php.net/manual/en/language.oop5.traits.phphere is a simple example to use namespace
<?php
namespace app\a{
class one{
public static function _1(){
echo 'a one _1<br>';
}
}
}
namespace app\b{
class one{
public static function _2(){
echo 'b one _2<br>';
}
}
}
namespace app{
echo a\one::_1();
echo b\one::_2();
echo a\two::_1();
}
namespace app\a{
class two{
public static function _1(){
echo 'a two _1<br>';
}
}
}
prints
a one _1
b one _2
a two _1
<?php
// multiple namespaces in a single file:
namespace foo{
class Cat {
static function says() {echo 'meoow';} }
}
namespace bar{
class Dog {
static function says() {echo 'ruff';} }
class Cat {
static function says() {echo 'meowi';} }
class Mouse { //nonstatic function
function says() {echo 'Come and get me ;)';} }
}
namespace animate{
class Animal {
static function breathes() {echo 'air';} }
}
namespace{ // No Namespace: global code
use foo as feline;
use bar as canine;
use bar\Mouse as MouseOnly;
use animate;
echo animate\Animal::breathes(), "<br />\n";
echo feline\Cat::says(), "<br />\n"; //not starting with a slash!
echo canine\Cat::says(), "<br />\n";
echo canine\Dog::says(), "<br />\n";
//any of the three following lines work:
// $micky=new bar\Mouse();
// $micky=new canine\Mouse();
$micky=new test();
echo $micky->says();
}
?>
