New in Latte 2.6: optional chaining and custom functions

Optional Chaining

Optional chaining lets us write code where Latte immediately stops evaluating expressions if it encounters null. With the new ? operator allowing optional access to variables or array elements. When we write code like

{$order?->id}

this is a way of saying that when $order is defined, $order->id will be computed, but when $order is null, stop what we’re doing and just return null.

You might find yourself using ? to replace a lot of code that performs repetitive nullish checks:

{$user?->address?->street}
// roughly means isset($user) && isset($user->address) ? $user->address->street : null

{$items[2]?->count}
// roughly means isset($items[2]) ? $items[2]->count : null

{$user->getIdentity()?->name}
// roughly means $user->getIdentity() !== null ? $user->getIdentity()->name : null

In the examples I write “roughly” because in fact the expression is evaluated more sophistically and no step is repeated. For example, $user->getIdentity() is called only once, so therefore the problem cannot occur because the method returns an object for the first time and null for the second time.

Optional chaining expressions can be used anywhere, for example in the conditions:

{if $blogPost?->count('*')}
	// means if (isset($blogPost) && $blogPost->count('*'))
	...
{/if}

Custom Functions

You can use all the global functions of PHP, but now also define your own:

$latte = new Latte\Engine;
$latte->addFunction('random', function (...$args) {
	return $args[array_rand($args)];
});

Or in presenter (requires nette/application v3.0.3):

$this->template->addFunction('random', function (...$args) {
	return array_rand($args);
});

The usage is then the same as when calling the PHP function:

{random(apple, orange, lemon)} // prints for example: apple

Support for custom features can be found in the new version of the Latte plugin for PhpStorm (so far in the beta version here).

As the picture suggests, a pair of isLinkCurrent() and isModuleCurrent() functions will automatically be available in the template along with the new version of nette/application.

<a n:href="Photo:" n:class="isLinkCurrent('Photo:') ? actual">Photogallery</a>