Tìm hiểu về Abstract và Interface

Thứ Hai, 23/11/2020

Tram Ho

1) Nội dung cơ bản:

A. Interface:

Cú pháp:

Khi sử dụng, từ khóa interface được khai báo.

Các Class con muốn sử dụng được cần có từ khóa implements.

<span class="token php language-php"><span class="token delimiter important">&lt;?php</span>
<span class="token keyword">interface</span> <span class="token class-name">InterfaceName</span> <span class="token punctuation">{</span>
  <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">name1</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">name2</span><span class="token punctuation">(</span><span class="token variable">$name</span><span class="token punctuation">,</span> <span class="token variable">$color</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">name3</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">:</span> string<span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token keyword">class</span> <span class="token class-name">Name</span> implement InterfaceName <span class="token punctuation">{</span>
  <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">name1</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
      <span class="token comment">//code//</span>
  <span class="token punctuation">}</span>
<span class="token punctuation">}</span>
<span class="token delimiter important">?&gt;</span></span>

<?php

interface InterfaceName {

public function name1();

public function name2($name, $color);

public function name3() : string;

}

class Name implement InterfaceName {

//code//

}

?>

Định nghĩa:

Cho phép chỉ định một lớp nên triển khai.

Nhiều class sử dụng chung cùng interface, gọi là đa hình.

B.Abstract:

Cú pháp:

<span class="token php language-php"><span class="token delimiter important">&lt;?php</span>
<span class="token keyword">abstract</span> <span class="token keyword">class</span> <span class="token class-name">ParentClass</span> <span class="token punctuation">{</span>
  <span class="token keyword">abstract</span> <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">someMethod1</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">abstract</span> <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">someMethod2</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
  <span class="token keyword">abstract</span> <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">someMethod3</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token delimiter important">?&gt;</span></span>

<?php

abstract class ParentClass {

abstract public function someMethod1();

abstract public function someMethod2();

abstract public function someMethod3();

}

?>

Từ khóa abstract được sử dụng trước class.

Class con kế thừa bằng extends

Khi một lớp con được kế thừa từ một lớp trừu tượng, chúng ta có các quy tắc sau:

Phương thức lớp con phải được định nghĩa với cùng tên và nó khai báo lại phương thức trừu tượng mẹ
Phương thức lớp con phải được xác định với công cụ sửa đổi quyền truy cập giống hoặc ít bị hạn chế hơn
Số lượng đối số bắt buộc phải giống nhau. Tuy nhiên, lớp con có thể có thêm các đối số tùy chọn

2) Ví dụ:

A. Abstract:

<span class="token php language-php"><span class="token delimiter important">&lt;?php</span> 
    <span class="token keyword">abstract</span> <span class="token keyword">class</span> <span class="token class-name">Info</span>
<span class="token punctuation">{</span>
    <span class="token keyword">public</span> <span class="token variable">$name</span><span class="token punctuation">;</span>
    <span class="token keyword">public</span> <span class="token variable">$age</span><span class="token punctuation">;</span>
    <span class="token keyword">abstract</span> <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">__construct</span><span class="token punctuation">(</span><span class="token variable">$name</span><span class="token punctuation">,</span> <span class="token variable">$age</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
    <span class="token keyword">abstract</span> <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">getInfo</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token keyword">class</span> <span class="token class-name">A</span> <span class="token keyword">extends</span> <span class="token class-name">Info</span>
<span class="token punctuation">{</span>
    <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">__construct</span><span class="token punctuation">(</span><span class="token variable">$name</span><span class="token punctuation">,</span> <span class="token variable">$age</span><span class="token punctuation">)</span>
    <span class="token punctuation">{</span>
        <span class="token variable">$this</span><span class="token operator">-</span><span class="token operator">&gt;</span><span class="token property">name</span> <span class="token operator">=</span> <span class="token variable">$name</span><span class="token punctuation">;</span>
        <span class="token variable">$this</span><span class="token operator">-</span><span class="token operator">&gt;</span><span class="token property">age</span>  <span class="token operator">=</span> <span class="token variable">$age</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
    <span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">getInfo</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token punctuation">{</span>
        <span class="token keyword">return</span> <span class="token variable">$this</span><span class="token operator">-</span><span class="token operator">&gt;</span><span class="token property">name</span> <span class="token punctuation">.</span> <span class="token single-quoted-string string">'-'</span> <span class="token punctuation">.</span> <span class="token variable">$this</span><span class="token operator">-</span><span class="token operator">&gt;</span><span class="token property">age</span><span class="token punctuation">;</span>
    <span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token variable">$a</span> <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">A</span><span class="token punctuation">(</span><span class="token single-quoted-string string">'hi'</span><span class="token punctuation">,</span> <span class="token number">18</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">echo</span> <span class="token variable">$a</span><span class="token operator">-</span><span class="token operator">&gt;</span><span class="token function">getInfo</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token delimiter important">?&gt;</span></span>

<?php

abstract class Info

{

public $name;

public $age;

abstract public function __construct($name, $age);

abstract public function getInfo();

}

class A extends Info

{

public function __construct($name, $age)

{

$this->name = $name;

$this->age = $age;

}

public function getInfo()

{

return $this->name . '-' . $this->age;

}

$a = new A('hi', 18);

echo $a->getInfo();

?>

B. Interface

<span class="token php language-php"><span class="token delimiter important">&lt;?php</span>
 <span class="token keyword">interface</span> <span class="token class-name">Height</span> <span class="token punctuation">{</span>
	<span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">__construct</span><span class="token punctuation">(</span><span class="token variable">$height</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token keyword">interface</span> <span class="token class-name">Height1</span> <span class="token punctuation">{</span>
	<span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">getHeight</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>

<span class="token keyword">class</span> <span class="token class-name">B</span> <span class="token keyword">implements</span> <span class="token class-name">Height</span><span class="token punctuation">,</span> Height1 <span class="token punctuation">{</span>
	<span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">__construct</span><span class="token punctuation">(</span><span class="token variable">$height</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
		<span class="token variable">$this</span><span class="token operator">-</span><span class="token operator">&gt;</span><span class="token property">height</span> <span class="token operator">=</span> <span class="token variable">$height</span><span class="token punctuation">;</span>
	<span class="token punctuation">}</span> 
	<span class="token keyword">public</span> <span class="token keyword">function</span> <span class="token function">getHeight</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
		<span class="token keyword">return</span> <span class="token variable">$this</span><span class="token operator">-</span><span class="token operator">&gt;</span><span class="token property">height</span><span class="token punctuation">;</span>
	<span class="token punctuation">}</span>
<span class="token punctuation">}</span>

<span class="token variable">$b</span> <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">B</span><span class="token punctuation">(</span><span class="token number">175</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">echo</span> <span class="token variable">$b</span><span class="token operator">-</span><span class="token operator">&gt;</span><span class="token function">getHeight</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>

<span class="token delimiter important">?&gt;</span></span>

<?php

interface Height {

public function __construct($height);

}

interface Height1 {

public function getHeight();

}

class B implements Height, Height1 {

public function __construct($height) {

$this->height = $height;

}

$b = new B(175);

echo $b->getHeight();

?>

Trong ví dụ này, có thể thấy được rằng 1 class implements từ nhiều interface. Khá thú vị phải không

3) Kết luận

Có thể hiểu nôm na rằng, 2 phương thức này dùng để tạo khung sườn cho project của chủng ta. Giúp ta làm việc nhanh chóng.

1 vài tài liệu tham khảo:

https://www.w3schools.com/php/php_oop_classes_abstract.asp
https://www.php.net/manual/en/function.interface-exist

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Tìm hiểu về Abstract và Interface

1) Nội dung cơ bản:

2) Ví dụ:

3) Kết luận

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