This article mainly introduces the variable functions of PHP, which has certain reference value. Now I share it with everyone. Friends in need can refer to it

PHP variable functions

Let me write my pseudocode first.

    protected $model;

    public function __construct(Category $category)
    {
        $this->model = $category;
    }

    public function getLists($request, $isPage = 'get', $order = 'created_at', $sort = 'desc')
    {
        return $this->model->orderBy($order, $sort)->$isPage();
    }

In getLists, there is a parameter of $isPage. The original intention is to pass in get to get all the data, and paginate to paginate. After I finished writing, I felt something was wrong. In our usual way of writing, find all data $this->model->orderBy($order, $sort)->get(); This is like this, I have never seen it used Variables to replace get(). In actual operation, the program executes normally. Then asked about this writing method in the forum. Next, we will introduce a concept, "Variable Function".

What is a variable function?

PHP supports the concept of variable functions. This means that if there are parentheses after a variable name, PHP will look for a function with the same name as the variable's value and try to execute it.

After understanding this concept, the above procedure will make sense. When the program is running, $isPage is replaced by get, and there is a parenthesis after $isPage, then the program will look for a function with the same name. Then continue execution.

Example:

<?php
function foo() {
    echo "In foo()<br />\n";
}

function bar($arg = &#39;&#39;) {
    echo "In bar(); argument was &#39;$arg&#39;.<br />\n";
}
$func = &#39;foo&#39;;
$func();        //  执行 foo(); 命令行中输出：In foo()<br />

$func = &#39;bar&#39;;
$func(&#39;test&#39;);   // 执行 bar();命令行中输出：In bar(); argument was &#39;test&#39;.<br />

Variable function syntax to call an object's method.

<?php
class Foo
{
    function Variable()
    {
        $name = &#39;Bar&#39;;
        $this->$name(); // This calls the Bar() method
    }

    function Bar()
    {
        echo "This is Bar";
    }
}

$foo = new Foo();
$funcname = "Variable";
$foo->$funcname();   // This calls $foo->Variable()

// 命令行执行输出： This is Bar

When calling static methods, function calls take precedence over static properties. Variable methods and static properties examples.

<?php
class Foo
{
    static $variable = &#39;static property&#39;;
    static function Variable()
    {
        echo &#39;Method Variable called&#39;;
    }
}

echo Foo::$variable; // This prints &#39;static property&#39;. It does need a $variable in this scope.
$variable = "Variable";
Foo::$variable();  // This calls $foo->Variable() reading $variable in this scope.

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