Magic constants

    There are nine magical constants that change depending on where they are used. For example, the value of __LINE__ depends on the line that it's used on in your script. All these "magical" constants are resolved at compile time, unlike regular constants, which are resolved at runtime. These special constants are case-insensitive and are as follows:

    PHP's magic constants
    Name Description
    __LINE__ The current line number of the file.
    __FILE__ The full path and filename of the file with symlinks resolved. If used inside an include, the name of the included file is returned.
    __DIR__ The directory of the file. If used inside an include, the directory of the included file is returned. This is equivalent to dirname(__FILE__). This directory name does not have a trailing slash unless it is the root directory.
    __FUNCTION__ The function name, or {closure} for anonymous functions.
    __CLASS__ The class name. The class name includes the namespace it was declared in (e.g. Foo\Bar). When used in a trait method, __CLASS__ is the name of the class the trait is used in.
    __TRAIT__ The trait name. The trait name includes the namespace it was declared in (e.g. Foo\Bar).
    __METHOD__ The class method name.
    __NAMESPACE__ The name of the current namespace.
    ClassName::class The fully qualified class name.

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    User Contributed Notes 3 notes

    up
    7
    Rich
    1 year ago
    <?php

    namespace My\App {
    class     Api {
    public static     fetch() {
    print     __FUNCTION__ . "\n"; // outputs fetch
    print __METHOD__ . "\n"; // outputs My\App\Api::fetch
    }
    }

    Api::fetch();
    }

    namespace {
    My\App\Api::fetch();
    }
    ?>

    __METHOD__ outputs a fully qualified method name; __FUNCTION__ when used in a method, outputs just the method name.
    up
    2
    chris at ocproducts dot com
    1 year ago
    Note that __CLASS__ and __METHOD__ both reference the class the code is written in, not whatever the object class is. E.g. if you have an object of class B inheriting from class A, any usage of __CLASS__ in class A is going to give "A".
    up
    2
    theking2 at king dot ma
    2 years ago
    If PHP is run inside a web server request there is an important difference between the __DIR__ constant and $_SERVER['DOCUMENT_ROOT'].

    Where __DIR__ of a PHP script contained within a sub-folder will include the complete server path $_SERVER['DOCUMENT_ROOT'] will contain a server path up to the _root_ of the application. This can be helpful when for instance an auto-loader is defined in an include file sitting inside a sub-folder and where the classes are located in another folder at the root of the application.
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