ABBA Handler

middleware.php

$stack = new \Aws\HandlerList(function () {
    echo "The main event!\n";
});

$stack->appendInit(function (callable $handler) {
    return function () use ($handler) {
        echo "Starting Middleware A\n";
        $handler();
        echo "Finishing Middleware A\n";
    };
});

$stack->appendInit(function (callable $handler) {
    return function () use ($handler) {
        echo "Starting Middleware B\n";
        $handler();
        echo "Finishing Middleware B\n";
    };
});

$fn = $stack->resolve();

$fn();