Laravel 助手接口

Question

简单的例子，我有以下帮助接口用于计算：

interface Calculation
{
    public function calculate();
}

还有几个实现这个接口的类：

class One implements Calculation
{
    public function calculate()
    {
        return some calculation;
    }
}


class Two implements Calculation
{
    public function calculate()
    {
        return some different calculation;
    }
}

// and so on..

现在，在我看来，我有下面显示的代码，但我希望能够摆脱 if's here。我希望能够做类似的事情：

foreach($units as $unit)
{
        $total = (new \App\Helpers\{$unit})->calculate();
}

我该怎么办？

foreach($units as $unit)
{
    if($unit === 'One')
    {
        $total = (new \App\Helpers\One)->calculate();
    }

    if($unit === 'Two')
    {
        $total = (new \App\Helpers\Two)->calculate();
    }

    if($unit === 'Three')
    {
        $total = (new \App\Helpers\Three)->calculate();
    }

    if($unit === 'Four')
    {
        $total = (new \App\Helpers\Four)->calculate();
    }

    // and so on..
}

Answer 1

试试这个代码：

   foreach($units as $unit)
    {
     $class="\\App\\Helpers\\".$unit;
     $total=(new $class)->calculate();
    }