如何在PHP中按字符串调用（执行）方法？

Question

Example:

final class A
{
    public static $instance;
    public static function get()
    {
        if (self::$instance === null)
            self::$instance = new self();
        return self::$instance;
    }
    public static function b()
    {
        return array('a','b','c');
    }
}

And Need to call the following method by string:

$callString = 'A::get()->b()';

How to call this via string?

Answer 1

Have you actually tried something? It's as simple as this:

final class A
{
    public static $instance;
    public static function get()
    {
        if (self::$instance === null)
            self::$instance = new self();
        return self::$instance;
    }
    public static function b()
    {
        return array('a','b','c');
    }
}

$class = 'A';//class name
$getter = 'get';//static method
$method = 'b';//public method
$instance = $class::getter();//calls A::get()
$array = $instance->{$method}();//gets array
//check with:
var_dump(
    $class::$getter()
        ->{$method}()
);

If you only have this string (A::get()->b()) to go on, you'll have to process/parse that string, and take it from there. A simple, but crude way to do so would be through regex:

$str = 'A::get()->b()';
preg_match_all('/(.+?)(::|\(\)-?>?)/', $str, $matches)
{
    $operators = $matches[2];//array('::', '()->', '()')
    $operands = $matches[1];//array('A', 'get', 'b');
    $result = null;
    for ($i=0, $j=count($operands);$i<$j;++$i)
    {
        $result = $operands[$i];//
        switch ($operator[$i])
        {
            case '::':
                $member = $operand[++$i];//next operand
                if (substr($opertator[$i],0,2) === '()')
                    $result = $result::$member();
                else
                    $result = $result::{$member};//static property
                break;
            case '()->'://non-static access
            case '()':
                $result = $result->{$operand[$i]}();
                break;
            default:
                $result = $result->{$operand[$i]};//non-static property
        }
    }
}

Note that this is un-tested, and very rough around the edges, but it should be enough to get you started.