Features like PHP

Object downward passing feature

When an object calls an instance method, and then statically calls a method of another class in the method, the object in the source method (this )

<code><span><span><?php </span><span><span>class</span><span>bee</span>{</span><span>public</span><span>$a</span> = <span>1</span>;
    <span>public</span><span><span>function</span><span>f</span><span>()</span>{</span><span>echo</span><span>$this</span>->a;
        <span>echo</span><span>'<br>'</span>;
        @lig::f();
    }
}

<span><span>class</span><span>lig</span>{</span><span>public</span><span>$a</span> = <span>2</span>;
    <span>public</span><span><span>function</span><span>f</span><span>()</span>{</span><span>echo</span><span>$this</span>->a;
    }
}

<span>$obj</span> = <span>new</span> bee();
<span>$obj</span>->f();</span></span></code>

static late static binding

static has 3 different meanings of syntax

• static variables in functions

<code><span><span>function</span><span>f</span><span>()</span>{</span><span>static</span><span>$v</span> = <span>1</span>;
}</code>

• static members in classes

<code><span><span>class</span><span>bee</span>{</span><span>static</span><span>$v</span> = <span>1</span>;
    <span>static</span><span><span>function</span><span>f</span><span>()</span>{</span>}
}</code>

• in methods Dynamically specify the 'current class', which is different from self. static represents the class that calls this method (dynamic), and self refers to the class where its code is located (static)

<code><span><span>class</span><span>bee</span>{</span><span>static</span><span>public</span><span>$a</span> = <span>10</span>;
    <span>static</span><span>public</span><span><span>function</span><span>f</span><span>()</span>{</span><span>echo</span> get_class().<span>':'</span>;
        <span>echo</span><span>self</span>::<span>$a</span>.<span>'-'</span>;
        <span>echo</span><span>static</span>::<span>$a</span>;
    }
}
<span><span>class</span><span>lig</span><span>extends</span><span>bee</span>{</span><span>static</span><span>public</span><span>$a</span> = <span>20</span>;

}

<span>echo</span> bee::f();
<span>echo</span><span>'<br>'</span>;
<span>echo</span> lig::f();</code>

Three major object-oriented ideas

• Package
  It is to encapsulate the data and try not to show it to others. It can be considered that the most basic encapsulation is to encapsulate a lot of data in a class, but more strictly speaking, it is to make the attributes private as much as possible and provide operations to the outside through shared methods. .
• Inheritance
• Polymorphism
  Usually refers to an object using the same method to obtain different results
  It also means that different objects use the same method to get different results

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The above has introduced the features of PHP, including aspects of it. I hope it will be helpful to friends who are interested in PHP tutorials.