PHP has large number of predefined constants. This HOWTO will present the seven most important, most practical and most useful PHP Magic Constants.

• __FILE__ – The full path and filename of the file.
• __DIR__ – The directory of the file.
• __FUNCTION__ – The function name.
• __CLASS__ – The class name.
• __METHOD__ – The class method name.
• __LINE__ – The current line number of the file.
• __NAMESPACE__ – The name of the current namespace

This is example PHP script with comments, which demonstrate howto use all previously mentioned PHP Magic Constants.

<?php

// Set namespace
namespace TestProject;

// This prints file full path and anme
echo ‘This file full path and file name is ‘ . __FILE__ . "\n";

// This prints file full path, without file name
echo ‘This file full path is ‘ . __DIR__ . "\n";

// This prints current line number on file
echo ‘This is line number ‘ . __LINE__ . "\n";

function test_function_magic_constant() {
    echo ‘This is from ‘ . __FUNCTION__ . "\n";
}

test_function_magic_constant();

class TestMagicConstants {
    // prints class name
    public function printClassName() {
        echo ‘This is ‘ . __CLASS__ . " class. \n";
    }

    // prints class and method name
    public function printMethodName() {
        echo ‘This is ‘ . __METHOD__ . " method\n";
    }

    // print function name
    public function printFunctionName() {
        echo ‘This is function ‘ . __FUNCTION__ . " inside class\n";
    }

    // prints namespace name
    public function printNamespace() {
        echo ‘Namespace name is ‘ . __NAMESPACE__ . "\n";
    }
}

$test_magic_constants = new TestMagicConstants;

$test_magic_constants->printClassName();

$test_magic_constants->printMethodName();

$test_magic_constants->printFunctionName();

$test_magic_constants->printNamespace();

RBAC(基于角色的访问控制权限)表结构原理分析

PHP __DIR__, __FILE__, __FUNCTION__, __CLASS__, __METHOD__, __LINE__, __NAMESPACE__