構文
Note that __FILE__ has a quirk when used inside an eval() call. It will tack on something like "(80) : eval()'d code" (the number may change) on the end of the string at run-time. The workaround is:
$script = php_strip_whitespace('myprogram.php');
$script = str_replace('__FILE__',"preg_replace('@\(.*\(.*$@', '', __FILE__,1)",$script);
eval($script);
自動的に定義される定数
PHPには実行されるスクリプトで使用可能な多くの 定義済みの定数があります。 しかし、これらの定数の多くは、種々の拡張モジュールにより作成され、 動的なロードやコンパイル時の組込みにより、これらの拡張モジュールが 使用可能である場合にのみ定義されます。
使われ方によって変化する自動的に定義される定数（マジカル定数）が 8 つあります。
例えば、__LINE__はスクリプト上において
呼び出された行番号です。特別定数は大文字小文字を区別しません。
内容は以下のとおりです:
| 名前 | 説明 |
|---|---|
__LINE__ |
ファイル上の現在の行番号。 |
__FILE__ |
ファイルのフルパスとファイル名。インクルードされるファイルの
中で使用された場合、インクルードされるファイルの名前が返されます。
PHP 4.0.2 以降では __FILE__
は常に絶対パスで、シンボリックリンクは解決されます。
それより前のバージョンでは、場合によっては相対パスが返されることもあります。
|
__DIR__ |
そのファイルの存在するディレクトリ。include の中で使用すると、 インクルードされるファイルの存在するディレクトリを返します。 つまり、これは dirname(__FILE__) と同じ意味です。 ルートディレクトリである場合を除き、ディレクトリ名の末尾にスラッシュはつきません (PHP 5.3.0 で追加されました)。 |
__FUNCTION__ |
関数名（PHP4.3.0で追加されました）。 PHP 5以降、この定数は宣言時の関数名(ケース依存)を返します。 PHP 4では、この値は常に小文字で返されました。 |
__CLASS__ |
クラス名（PHP4.3.0で追加されました）。 PHP 5以降、この定数は宣言時のクラス名(ケース依存)を返します。 PHP 4では、この値は常に小文字で返されました。 クラス名には、そのクラスが宣言されている名前空間も含みます (例 Foo\Bar)。 PHP 5.4 以降では、__CLASS__ がトレイトでも使えることに注意しましょう。トレイトのメソッド内で __CLASS__ を使うと、そのトレイトを use しているクラスの名前を返します。 |
__TRAIT__ |
トレイト名 (PHP 5.4.0 で追加されました)。PHP 5.4 以降では、 この定数はトレイト名を宣言時のままで返します (大文字小文字を区別します)。 トレイト名には、宣言された名前空間も含みます (例 Foo\Bar)。 |
__METHOD__ |
クラスのメソッド名（PHP5.0.0で追加されました）。 メソッド名は宣言時と同じ(ケース依存)を返します。 |
__NAMESPACE__ |
現在の名前空間の名前 (大文字小文字を区別します)。 この定数はコンパイル時に定義されます (PHP 5.3.0 で追加されました)。 |
get_class(), get_object_vars(), file_exists(), function_exists()も参照してください。
add a note
User Contributed Notes
自動的に定義される定数 - [25 notes]
user9 at voloreport dot com ¶
1 year ago
madboyka at yahoo dot com ¶
2 years ago
Since namespace were introduced, it would be nice to have a magic constant or function (like get_class()) which would return the class name without the namespaces.
On windows I used basename(__CLASS__). (LOL)
vijaykoul_007 at rediffmail dot com ¶
7 years ago
the difference between
__FUNCTION__ and __METHOD__ as in PHP 5.0.4 is that
__FUNCTION__ returns only the name of the function
while as __METHOD__ returns the name of the class alongwith the name of the function
class trick
{
function doit()
{
echo __FUNCTION__;
}
function doitagain()
{
echo __METHOD__;
}
}
$obj=new trick();
$obj->doit();
output will be ---- doit
$obj->doitagain();
output will be ----- trick::doitagain
david at thegallagher dot net ¶
1 year ago
You cannot check if a magic constant is defined. This means there is no point in checking if __DIR__ is defined then defining it. `defined('__DIR__')` always returns false. Defining __DIR__ will silently fail in PHP 5.3+. This could cause compatibility issues if your script includes other scripts.
Here is proof:
<?php
echo (defined('__DIR__') ? '__DIR__ is defined' : '__DIR__ is NOT defined' . PHP_EOL);
echo (defined('__FILE__') ? '__FILE__ is defined' : '__FILE__ is NOT defined' . PHP_EOL);
echo (defined('PHP_VERSION') ? 'PHP_VERSION is defined' : 'PHP_VERSION is NOT defined') . PHP_EOL;
echo 'PHP Version: ' . PHP_VERSION . PHP_EOL;
?>
Output:
__DIR__ is NOT defined
__FILE__ is NOT defined
PHP_VERSION is defined
PHP Version: 5.3.6
Anonymous ¶
1 year ago
Further clarification on the __TRAIT__ magic constant.
<?php
trait PeanutButter {
function traitName() {echo __TRAIT__;}
}
trait PeanutButterAndJelly {
use PeanutButter;
}
class Test {
use PeanutButterAndJelly;
}
(new Test)->traitName(); //PeanutButter
?>
chris dot kistner at gmail dot com ¶
2 years ago
There is no way to implement a backwards compatible __DIR__ in versions prior to 5.3.0.
The only thing that you can do is to perform a recursive search and replace to dirname(__FILE__):
find . -type f -print0 | xargs -0 sed -i 's/__DIR__/dirname(__FILE__)/'
michiel ed thalent circle nl ¶
8 months ago
__METHOD__ will return bother the method name, as the class and namespace name.
__FUNCTION__ will only return the method name.
<?php
namespace General;
class ArgumentValidation {
public static function validateIntArguments() {
echo __FUNCTION__ . "\n";
echo __METHOD__ . "\n";
}
}
ArgumentValidation::validateIntArguments(new ArgumentValidation);
?>
Will return:
validateIntArguments
General\ArgumentValidation::validateIntArguments
If you want to get a ReflectionMethod instance of your sattis method is to use __FUNCTION__.
$refl = new \ReflectionMethod(__CLASS__, __FUNCTION__);
php at kennel17 dot co dot uk ¶
5 years ago
In response to stangelanda at gmail dot com, (who suggested a possible fix to get the actual class name of the object, when being called statically).
in PHP5, this fix no longer works.
Here is some example code:
<?php
function get_class_static() {
$bt = debug_backtrace();
$name = $bt[1]['class'];
return $name;
}
class foo {
function printClassName() {
print(get_class_static() . "<br>");
}
}
class bar extends foo {
}
$f = new foo();
$b = new bar();
$f->printClassName();
$b->printClassName();
?>
In PHP4, it outputs
foo
bar
as you described.
However, in PHP5, due to the way the debug_backtrace() function has been modified (see http://bugs.php.net/bug.php?id=30828) the output is now
foo
foo
I have yet to figure out a way to get the original output in PHP5. Any suggestions would be very useful, and if I find an answer I'll post it here.
darwin[at]buchner[dot]net ¶
11 years ago
As of version 4.0.6, there is also a handy predefined DIRECTORY_SEPARATOR constant which you can use to make you scripts more portatable between OS's with different directory structures.
Anonymous ¶
11 months ago
A note about __FUNCTION__ and create_function():
If you use __FUNCTION__ inside the body of a function you create with create_function(), the __FUNCTION__ always evaluates to the string "__lambda_func" (even in different functions created by create_function()), not the function name that is returned by create_function().
tc0nn ¶
1 year ago
Also worth noting, I use a extreme-logger when doing intense troubleshooting. It basically does a debug_backtrace and logs certain info. I noticed on some older PHP installs (<5) I had to prepend __FILE__ and __LINE__ with ''. just to force PHP output a string. Specifically I was loading those two in an array which were concat'd onto a log file eventually.
example:
if($a['debug']){$of->logger(array('file'=>__FILE__,'line'=>''.__LINE__,'data'=>$sql_data_array));}
Jamie ¶
2 years ago
Note that as mentioned, __FILE__ resolves any aliases. Other real path information, such as $_SERVER["SCRIPT_FILENAME"], doesn't.
__FILE__ => /volume1/web/mysite/admin/inc/includeFile.inc.php
$_SERVER["SCRIPT_FILENAME"] => /var/services/web/mysite/admin/products.php
If you need to compare one with the other, use
realpath($_SERVER["SCRIPT_FILENAME"])
me at jamessocol dot com ¶
4 years ago
We need an eighth magic constant, something along the lines of __STATIC__. This should return the name of the class from which a static method was called, regardless of where in the inheritance tree the method was defined.
PHP 5.3 has the new use of the static keyword which will help, but it isn't perfect. You still have to repeat yourself frequently.
For example, trying to implement Active Record:
<?php
// In PHP 5.3
class Model
{
public static function find()
{
echo static::$class;
}
}
class Product extends Model
{
protected static $class = __CLASS__;
}
class User extends Model
{
protected static $class = __CLASS__;
}
Product::find(); // "Product"
User::find(); // "User"
?>
<?php
// With __STATIC__ keyword. (Would be better.)
class Model
{
public static function find()
{
echo __STATIC__;
}
}
class Product extends Model {}
class User extends Model {}
Product::find(); // "Product"
User::find(); // "User"
?>
[EDITED : Use get_called_class()]
php at kennel17 dot co dot uk ¶
5 years ago
Further to my previous note, the 'object' element of the array can be used to get the parent object. So changing the get_class_static() function to the following will make the code behave as expected:
<?php
function get_class_static() {
$bt = debug_backtrace();
if (isset($bt[1]['object']))
return get_class($bt[1]['object']);
else
return $bt[1]['class'];
}
?>
HOWEVER, it still fails when being called statically. Changing the last two lines of my previous example to
<?php
foo::printClassName();
bar::printClassName();
?>
...still gives the same problematic result in PHP5, but in this case the 'object' property is not set, so that technique is unavailable.
Tomek Perlak [tomekperlak at tlen pl] ¶
6 years ago
The __CLASS__ magic constant nicely complements the get_class() function.
Sometimes you need to know both:
- name of the inherited class
- name of the class actually executed
Here's an example that shows the possible solution:
<?php
class base_class
{
function say_a()
{
echo "'a' - said the " . __CLASS__ . "<br/>";
}
function say_b()
{
echo "'b' - said the " . get_class($this) . "<br/>";
}
}
class derived_class extends base_class
{
function say_a()
{
parent::say_a();
echo "'a' - said the " . __CLASS__ . "<br/>";
}
function say_b()
{
parent::say_b();
echo "'b' - said the " . get_class($this) . "<br/>";
}
}
$obj_b = new derived_class();
$obj_b->say_a();
echo "<br/>";
$obj_b->say_b();
?>
The output should look roughly like this:
'a' - said the base_class
'a' - said the derived_class
'b' - said the derived_class
'b' - said the derived_class
stangelanda at gmail dot com ¶
6 years ago
claude noted that __CLASS__ always contains the class that it is called in, if you would rather have the class that called the method use get_class($this) instead. However this only works with instances, not when called statically.
<?php
class A {
function showclass() {
echo get_class($this);
}
}
class B extends A {}
$a = new A();
$b = new B();
$a->showclass();
$b->showclass();
A::showclass();
B::showclass();
//results in "a", "b", false, false
?>
I tried keeping track of the class manually within the properties, but the following doesn't work either:
<?php
class A {
var $class = __CLASS__;
function showclass() {
echo $this->class;
}
}
class B extends A {
var $class = __CLASS__;
}
//results in "a", "b", NULL, NULL
?>
The best solution I could come up with was using debug_backtrace. I assume there is a better way somehow, but I can't find it. However the following works:
<?php
class A {
function showclass() {
$backtrace = debug_backtrace();
echo $backtrace[0]['class'];
}
}
class B extends A {}
//results in "a", "b", "a", "b"
?>
warhog at warhog dot net ¶
7 years ago
There is another magic constant not mentioned above: __COMPILER_HALT_OFFSET__ - contains where the compiler halted - see http://www.php.net/manual/function.halt-compiler.php for further information.
karl __at__ streetlampsoftware__dot__com ¶
8 years ago
Note that the magic constants cannot be included in quoted strings.
For instance,
echo "This is the filename: __FILE__";
will return exactly what's typed above.
echo "This is the filename: {__FILE__}";
will also return what's typed above.
The only way to get magic constants to parse in strings is to concatenate them into strings:
echo "This is the filename: ".__FILE__;
csaba at alum dot mit dot edu ¶
8 years ago
Sometimes you might want to know whether a script is the top level script or whether it has been included. That could be useful if you want to reuse the routines in another script, but you don't want to separate them out. Here's a way that seems to be working for me (for both Apache2 module and CLI versions of PHP) on my Win XP Pro system.
By the way, if __FILE__ is within a function call, its value corresponds to the file it was defined in and not the file that it was called from. Also, I used $script and strtolower instead of realpath because if the script is deleted after inclusion but before realpath is called (which could happen if the test is deferred), then realpath would return empty since it requires an extant file or directory.
Csaba Gabor from Vienna
<?php
if (amIincluded()) return; // if we're included we only want function defs
function amIincluded() {
// returns true/false depending on whether the currently
// executing script is included or not
// Don't put this function in an include file (duh)!
$webP = !!$_SERVER['REQUEST_METHOD']; // a web request?
$script = preg_replace('/\//',DIRECTORY_SEPARATOR,
$_SERVER['SCRIPT_FILENAME']);
return ($webP) ? (strtolower(__FILE__)!=strtolower($script)) :
!array_key_exists("_REQUEST", $GLOBALS);
}
?>
claude at NOSPAM dot claude dot nl ¶
8 years ago
Note that __CLASS__ contains the class it is called in; in lowercase. So the code:
class A
{
function showclass()
{
echo __CLASS__;
}
}
class B extends A
{
}
$a = new A();
$b = new B();
$a->showclass();
$b->showclass();
A::showclass();
B::showclass();
results in "aaaa";
jrivero24 at yahoo dot es ¶
1 year ago
When __DIR__ is not defined, prior 5.3.0:
<?php if ( !defined('__DIR__') ) define('__DIR__', dirname(__FILE__)); ?>
stefan at efectos dot nl ¶
2 years ago
When __DIR__ is not defined, you can also use this workaround to generate it:
<?php
if(!defined('__DIR__')) {
$iPos = strrpos(__FILE__, "/");
define("__DIR__", substr(__FILE__, 0, $iPos) . "/");
}
?>
Keep in mind this sets __DIR__ to the directory you are running this snippet from.
lm arobase bible point ch ¶
8 years ago
in reply to x123 at bestof dash inter:
I believe, this is not a bug, but a feature.
__FILE__ returns the name of the include file, while $PHP_SELF returns the relative name of the main file.
It is then easy to get the file name only with substr(strrchr($PHP_SELF,'/'),1)