如何使用 PHP7 从静态方法调用特征的非静态方法？

Question

trait ClearFolder
{
    public function clearFolder($dir)
    {
        //codes...
    }

    public function clearInFolder($dir)
    {
        $this->clearFolder($dir);

        mkdir($dir);
    }
}

use boot\library\traits\ClearFolder;

class FileCache
{
    //codes....

    use ClearFolder;
    public static function clearAll()
    {
        //Case1. Uncaught Error: Using $this when not in object...   
        $this->clearInFolder(self::$storage . '/');

        //Case2. Non-static method boot\libr... should not be called statically 
        self::clearInFolder(self::$storage . '/');

        //Case3. Cannot instantiate trait...
        $trait = new ClearFolder;

    }
}

To use a non-static method of another class inside a static method, I have to create an instance with the new keyword. But I can't use 'new' with a trait.

And I use 'declare (strict_types = 1);' and ' error_reporting(E_ALL);'.

Should I change the trait's method statically and replace everything that uses the trait?

Answer 1

If you want to use a non static function from a trait you must create a instance:

trait trait1
{
    public function dummy()
    {
      var_dump("fkt dummy");
    }
}
class c1{
  use trait1;

  public static function static1(){
    (new static)->dummy();
  }
}

c1::static1();  //string(9) "fkt dummy"

Or you declare your function in the trait as static:

trait trait1
{
    public static function dummy()
    {
      var_dump("fkt dummy");
    }
}
class c1{
  use trait1;
} 

c1::dummy(); //string(9) "fkt dummy"

Not nice, but works. But you should not use this without thinking about your code design.