PHP7.1新特性

#php5
function($a = null){
  if($a===null) {
    return null;
  }
  return $a;
}
#php7+
function fun() :?string
{
  return null;
}

function fun1(?$a)
{
  var_dump($a);
}
fun1(null);//null
fun1('1');//1

function fun() :void
{
  echo "hello world";
}

class Something
{
    const PUBLIC_CONST_A = 1;
    public const PUBLIC_CONST_B = 2;
    protected const PROTECTED_CONST = 3;
    private const PRIVATE_CONST = 4;
}

function iterator(iterable $iter)
{
    foreach ($iter as $val) {
        //
    }
}

try {
    // some code
} catch (FirstException | SecondException $e) {
    // handle first and second exceptions
}

$data = [
    ["id" => 1, "name" => 'Tom'],
    ["id" => 2, "name" => 'Fred'],
];

// list() style
list("id" => $id1, "name" => $name1) = $data[0];
var_dump($id1);//1

$a= "hello";
$a[-2];//l

<?php
class Test
{
    public function exposeFunction()
    {
        return Closure::fromCallable([$this, 'privateFunction']);
    }

    private function privateFunction($param)
    {
        var_dump($param);
    }
}

$privFunc = (new Test)->exposeFunction();
$privFunc('some value');