get_called_class（）和static :: class之间的区别

What is the difference between calling get_called_class() and static::class inside a static class method?

For example:

class Base
{
    public static function foo()
    {
        return static::class;
    }

    public static function bar()
    {
        return get_called_class();
    }
}

class Child extends Base {}

echo Base::foo();  // prints 'Base'
echo Base::bar();  // prints 'Base'
echo Child::foo(); // prints 'Child'
echo Child::bar(); // prints 'Child'

It appears to work the same in both cases but there may be some nuances I should be aware of.

static::class was "only" added in PHP 5.5, but other than that they should work identically.

From a quick test, static::class appears to be slightly faster. Using the code from the question:

profile("Parent, static::class", function () { Base::foo();});
profile("Parent, get_called_class", function () { Base::bar();});
profile("Child, static::class", function () { Child::foo();});
profile("Child, get_called_class", function () { Child::bar();});

Parent, static::class took 0.0467 seconds

Parent, get_called_class took 0.0559 seconds

Child, static::class took 0.0468 seconds

Child, get_called_class took 0.0554 seconds

But you've got to be doing well into six-figures worth of iterations to notice. See https://3v4l.org/qaXln (3v4l definitely isn't the best tool for benchmarking, but there's enough of a pattern)