PHP语法-花括号

Question

So I have a simple class;

class Foo{
      public function bar(){
      // Do something
      }
}
$method = 'bar';
$object = new Foo;

Using

$object->{ $method }()

seems to work the same as writing

$object->$method()

Is there any difference between these and if not, why would you write it one way or the other?

Answer 1

Difference between these styles become significant when instead of simple $method you use, for example, this:

class Baz {
    public function getMethodName()
    {
        return 'bar';
    }
}

class Foo{
      public function bar(){
        echo 'bar_run';
      }
}
$method = 'bar';
$object = new Foo;
$yao = new Baz();
// see this line:
$object->{$yao->getMethodName()}();   // outputs `bar_run`

// if you omit `{}`:
$object->$yao->getMethodName()();     // fatal error

So, {} should be used when it's not clear how to parse your code.

Of course, such codes like $object->{$yao->getMethodName()}(); must be avoided. But still if there's some case in which it's not clearly understood how to execute an expression - better use {} .