The differences and similarities between new static() and new self(), staticself_PHP tutorial

The differences and similarities between new static() and new self(), staticself

The night is long!

Today I led the team to build a local website. I found that I couldn’t build it with PHP 5.2. The PHP code of the website contained many parts that were above 5.3. My boss asked me to change it so that it could run under 5.2.

I changed and found a place

<span>return</span> <span>new</span> <span>static</span>(<span>$val</span>);

This damn horse is amazing, I’ve only seen it before

<span>return</span> <span>new</span> self(<span>$val</span>);

So I checked online to find out the difference between the two.

self - This is this class, this class in the code segment.

static - PHP 5.3 only adds the current class, which is a bit like $this. It is extracted from the heap memory and accesses the currently instantiated class, so static represents that class.

Let’s take a look at the professional explanations from foreigners.

self refers to the same class whose method the new operation takes place in.

static in PHP 5.3's late static bindings refers to whatever class in the hierarchy which you call the method on.

In the following example, B inherits both methods from A. self is bound to A because it's defined in A's implementation of the first method, whereas static is bound to the called class (also see <span><span>get_called_class()</span></span> ).

<span>class</span><span> A {
    </span><span>public</span> <span>static</span> <span>function</span><span> get_self() {
        </span><span>return</span> <span>new</span><span> self();
    }

    </span><span>public</span> <span>static</span> <span>function</span><span> get_static() {
        </span><span>return</span> <span>new</span> <span>static</span><span>();
    }
}

</span><span>class</span> B <span>extends</span><span> A {}

</span><span>echo</span> <span>get_class</span>(B::get_self());  <span>//</span><span> A</span>
<span>echo</span> <span>get_class</span>(B::get_static()); <span>//</span><span> B</span>
<span>echo</span> <span>get_class</span>(A::get_static()); <span>//</span><span> A</span>

This example is basically easy to understand at a glance.

I understand the principle, but the problem has not been solved yet. How to solve the problem of return new static($val);?

In fact, it’s easy to use get_class($this); 如下

<span>class</span><span> A {
    </span><span>public</span> <span>function</span><span> create1() {
        </span><span>$class</span> = <span>get_class</span>(<span>$this</span><span>);<br /></span><span>　　　　return</span> <span>new</span> <span>$class</span><span>();
    }
    </span><span>public</span> <span>function</span><span> create2() {
        </span><span>return</span> <span>new</span> <span>static</span><span>();
    }
}

</span><span>class</span> B <span>extends</span><span> A {

}

</span><span>$b</span> = <span>new</span><span> B();
</span><span>var_dump</span>(<span>get_class</span>(<span>$b</span>->create1()), <span>get_class</span>(<span>$b</span>-><span>create2()));

</span><span>/*</span><span>
The result 
string(1) "B"
string(1) "B"
</span><span>*/</span>

What is the difference between C++ new and new[]?

There are a lot of things. hehe. Let me tell you in detail.
1. The difference between new and new[]
New is used to create a single object or instance, which is to call the constructor of a class.
new [] is used to create an array instance of an object or instance, and the addresses are consecutive. (Memory allocation may not be continuous, but the address list is continuous.)
2. Virtual function (I can’t explain this, I can only give examples)
class person
{
public:
virtual say();
}
class techer : public person
{
public :
protected override say();
}
class student : public person
{
public :
protected override say();
}
The third one didn’t understand what it meant.
I don’t know if you understand the first two. If not, contact me.

static A a=new A() What is the use of static in JAVA? Be specific

In java,
public static void main(String args[]) is a main method.
A java program can have multiple methods, but there can only be one main method.
Use The method modified by ststic is called a class method (main is also a class method).
A a=new A() creates an instance object static and serves as a decoration

http://www.bkjia.com/PHPjc/867540.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/867540.htmlTechArticleThe differences and similarities between new static() and new self(), staticself is a long night! Today, I led the team to build a local website. I found that it cannot be built with PHP 5.2. There are many PHP codes in the site that are above 5.3...