PHP: Hypertext Preprocessor (original) (raw)
Magic constants
There are a few magical constants that change depending on where they are used. For example, the value of**[__LINE__](language.constants.magic.php#constant.line)** depends on the line that it's used on in a 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 inside 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. |
| __PROPERTY__ | Only valid inside aproperty hook. It is equal to the name of the property. |
| __NAMESPACE__ | The name of the current namespace. |
| ClassName::class | The fully qualified class name. |
Found A Problem?
1 year ago
`<?phpnamespace 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.`
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".
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.
`