使字符串对象？

I'm having a problem when converting a string to an object. Here is the function:

public function slikepoid($dire,$id)
{
    $this->dire=$dire;
    $this->id=$id;
    $slike = $this->skupljanjeslika($this->dire);
    $slikeid = array_filter($slike, function($el) { 
        return substr( $el, 0, 2) == '$this->id-'; // Here is the problem !
    });
    return $slikeid;
}

I got this error:

Fatal error: Using $this when not in object context on line 8

I tried:

 return substr( $el, 0, 2) == ''.(string)$this->id;'-'; 

But no luck :(

You should be able to use a closure to accomplish this:

$slikeid = array_filter($slike, function($el) use( $id) { 
    return substr( $el, 0, 2) == $id; 
});

Now, $id should be inside the scope of the anonymous function, so you should be able to compare the element value against it.