PHP implements a way to reuse code called Traits. The trait_exists() function in PHP is an inbuilt function that is used to check whether a trait exists or not. This function accepts the traitname and autoload as parameters and returns true if trait exists, false if not, null in case of an error.
Syntax :
trait_exists ( string $traitname , bool $autoload = ? ) : bool
Parameters: This function accepts two parameters as mentioned above and described below.
- $traitname: This parameter contains the name of the trait.
- $autoload: This parameter is a boolean value that tells whether to autoload, if not already loaded.
Return Value:
- It returns true, if a trait exists.
- It returns false, if the trait does not exist.
- It returns null for any error encountered.
Example 1:
PHP
<?php // Created trait Programming trait Programming { // Declared static instance private static $instance; protected $temp; // Defining static function in trait to Reuse public static function Designing() { self::$instance = new static(); // Magic constant __TRAIT__ in PHP // It gets the class name for the static method called. self::$instance->temp = get_called_class().' '.__TRAIT__; return self::$instance; } } // Checking if 'Programming' Trait exists if ( trait_exists( 'Programming' ) ) { class Initializing { // Reusing trait 'Programming' use Programming; public function text( $strParam ) { return $this->temp.$strParam; } } } echo Initializing::Designing()->text('!!!'); ?> |
Output:
Initializing Programming!!!
Example 2:
PHP
<?php // Creating Base class class Base { public function callBase() { echo 'This is base function!'."<br>"; } } // Creating Trait trait myTrait { public function callBase() { parent::callBase(); echo 'This is trait function!'."<br>"; } } // Using myTrait class myClass extends Base { use myTrait; } $myObject = new myClass(); $myObject->callBase(); // Checking if trait exists if(trait_exists( "myTrait")) { echo "\n myTrait exists! \n"; } else{ echo "\n myTrait does not exists! \n"; } ?> |
Output:
This is base function! This is trait function! myTrait exists!
Reference : https://www.php.net/manual/en/function.trait-exists.php
