PHP Type Hint Closure vs callable

Posted

Closure 和 callable Type Hint 差異

Two functions

function testClosure(Closure $closure)
{
    $closure();
}

function testCallable(callable $callable)
{
    $callable();
}

Use normal function

function foo()
{
    echo 'bar';
}

testClosure('foo');
// PHP Fatal error:  Uncaught TypeError:
// Argument 1 passed to testClosure() must be an instance of Closure, string given

testCallable('foo');
// bar

Use anonymous function

testClosure(function () {
    echo 'baz';
});
// baz

testCallable(function () {
    echo 'baz';
});
// baz

差別在於 Closure 只能用在匿名函式，callable 則是兩者都可。

References