PHP: rfc:throw_expression

Operator precedence

If throw becomes an expression operator precedence becomes relevant. These examples are working today.

throw $this->createNotFoundException();
// Evaluated as
throw ($this->createNotFoundException());
// Instead of
(throw $this)->createNotFoundException();
 
throw static::createNotFoundException();
// Evaluated as
throw (static::createNotFoundException());
// Instead of
(throw static)::createNotFoundException();
 
throw $userIsAuthorized ? new ForbiddenException() : new UnauthorizedException();
// Evaluated as
throw ($userIsAuthorized ? new ForbiddenException() : new UnauthorizedException());
// Instead of
(throw $userIsAuthorized) ? new ForbiddenException() : new UnauthorizedException();
 
throw $maybeNullException ?? new Exception();
// Evaluated as
throw ($maybeNullException ?? new Exception());
// Instead of
(throw $maybeNullException) ?? new Exception();
 
throw $exception = new Exception();
// Evaluated as
throw ($exception = new Exception());
// Instead of
(throw $exception) = new Exception();
 
throw $exception ??= new Exception();
// Evaluated as
throw ($exception ??= new Exception());
// Instead of
(throw $exception) ??= new Exception();
 
throw $condition1 && $condition2 ? new Exception1() : new Exception2();
// Evaluated as
throw ($condition1 && $condition2 ? new Exception1() : new Exception2());
// Instead of
(throw $condition1) && $condition2 ? new Exception1() : new Exception2();

The common theme here is that everything after the throw keyword has a higher precedence. For this reason this RFC proposes to use the lowest operator precedence possible. All the current code, even if broken or strange, will continue behaving the same way. This isn't a problem because generally throw should be the last operator you're using as every expression after it wouldn't be evaluated anyway.

The only downside of the low precedence is that a throw between two short-circuit operators would not be possible without parentheses:

$condition || throw new Exception('$condition must be truthy')
  && $condition2 || throw new Exception('$condition2 must be truthy');
// Evaluated as
$condition || (throw new Exception('$condition must be truthy') && $condition2 || (throw new Exception('$condition2 must be truthy')));
// Instead of
$condition || (throw new Exception('$condition must be truthy'))
  && $condition2 || (throw new Exception('$condition2 must be truthy'));

But I see little use for code like this.