[RFC] Guard statement

[alherd-by]

I want to propose new decision-making statement - guard. It is similar to if, but executes body only if expression equals false and must contains code that changes flow of execution: throw, return etc.

guard ($condition = false) else {
     //code
     thrown new \LogicException();
}

Inspired by Swift lang https://docs.swift.org/swift-book/ReferenceManual/Statements.html#grammar_if-statement

Work in progress.

[zmitic]

Is it possible to have something similar to arrow functions syntax? For comparison:

// some controller:

public function edit(Product $product): Response
{
    guard($user = $this->getUser()) => new RedirectResponse();
    guard($product->getOwner() === $user) => throw new SecurityException();
}

vs

// some controller:

public function edit(Product $product): Response
{
    if (!$user = $this->getUser()) {
        return  new RedirectResponse();
    }
    if ($product->getOwner() !== $user) {
        throw new SecurityException();
    }
}

First example with short guard is much cleaner and shorter when compared to assignments in if and negative comparison.

In reality, most usages for this is early-exit and unlikely to have more than 1 line of code (even RFC has such examples).

[alherd-by]

Withdrawn