在重构代码时需要帮助解决PHP中的类未找到错误

Question

I have just started digging into PHP OOPs concept. For this I have created a Class and an Interface in the same file. Everything works well till this moment. Further I started refactoring my code and separated both Class and Interface to their respective files. After this I am getting below error:

Fatal error: Interface 'TaskInterface' not found in E:\www\project\oop\Tasks.php on line 4

Below line solve that error, however I need a way to resolve it through Composer and Namespace.

require 'TaskInterface.php';

Both of the files are under same directory level.

Class Tasks: (Tasks.php)

use App\TaskInterface;
require_once 'vendor/autoload.php';
class Tasks implements TaskInterface {
 public function create()
 {
    var_dump('created');
 }
}
$obj = new Tasks();
echo $obj->create();

Interface Task: (TaskInterface.php)

namespace App;
interface TaskInterface {
 public function create();
}

Here is composer.json code to autoload class/interface:

{
"name" : "OOP",
"autoload": {
    "psr-4": {
        "App\\": "project/oop/"
    }
 }
}

Project URL: http://localhost/project/oop/tasks.php

Directory Structure:

|project
|oop
  -|vendor
     -|composer (containing all auto generated files)
     -|autoload.php
  -|composer.json
  -|TaskInterface.php
  -|Tasks.php

Answer 1

I'm not certain which step you're missing, but this should be a fully working example.

Assuming the following directory structure:

├── composer.json
├── project
│   └── oop
│       ├── TaskInterface.php
│       └── Tasks.php
└── vendor
    ├── autoload.php

project/oop/TaskInterface.php

<?php
namespace App;

interface TaskInterface {
  public function create();
}

project/oop/Tasks.php

<?php
namespace App;

require_once(__DIR__ . '/../../vendor/autoload.php');

class Tasks implements TaskInterface {
  public function create()
  {
    var_dump('created');
  }
}

$obj = new Tasks();
echo $obj->create();

composer.json

{
  "name" : "OOP",
  "autoload": {
    "psr-4": {
      "App\\": "project/oop/"
    }
 }
}

---

$ composer dump-autoload
Generating autoload files

$ php project/oop/Tasks.php
string(7) "created"

The important parts

• Every file containing a class or interface definition should declare a namespace
• Deeper namespace declarations will be looked up in deeper directories underneath project/oop/. If you declare a class Product in the App/Foo namespace, your source file would need to be in project/oop/Foo/Product.php.
• When referencing a class or interface in the same namespace as the current file, you don't need a use statement
• The entry-point (in this case Tasks.php) must include the Composer autoloader
• You wouldn't normally mix a class definition and procedural code as you have done in Tasks.php, but there's no reason it won't work like that. More commonly, you'd have a shared "front-controller" higher up the directory structure somewhere that would include the autoloader and any other bootstrapping.