trait_exists

(PHP 5 >= 5.4.0, PHP 7, PHP 8)

trait_existsChecks if the trait exists

Descrizione

trait_exists(string $trait, bool $autoload = true): bool

Elenco dei parametri

trait

Name of the trait to check

autoload

Whether to autoload if not already loaded.

Valori restituiti

Returns true if trait exists, and false otherwise.

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User Contributed Notes 3 notes

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10
Lubaev.K
11 years ago
<?php
trait World {

    private static
$instance;
    protected
$tmp;

    public static function
World()
    {
       
self::$instance = new static();
       
self::$instance->tmp = get_called_class().' '.__TRAIT__;
       
        return
self::$instance;
    }

}

if (
trait_exists( 'World' ) ) {
   
    class
Hello {
        use
World;

        public function
text( $str )
        {
            return
$this->tmp.$str;
        }
    }

}

echo
Hello::World()->text('!!!'); // Hello World!!!
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3
astinus dot eberhard at gmail dot com
7 years ago
Traits are compatible with class autoload mechanism - in fact, if you look at source code of trait_exists function, you will find similar peace of code (see Zend/zend_builtin_functions.c)
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0
valerio dot bozzolan at gmail dot com
8 years ago
What is the default value of $autoload? And in which way traits are autoloaded? Is there something as spl_autoload() for traits?
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