Re: [RFC] Void Return Type (v0.2, reöp ening)

Hi Levi, Levi Morrison wrote:

On Wed, Oct 14, 2015 at 4:00 PM, Stanislav Malyshev <smalyshev@gmail.com> wrote:

Hi!

I'm reviving my Void Return Type RFC, this time for PHP 7.1: https://wiki.php.net/rfc/void_return_type Please read it and tell me your thoughts!

I still see no point in this, as every PHP function actually returns something (at least null). So this type would not actually be right and would not reflect what actually is happening.

I agree that void doesn't make sense given that we document that return; will return null[1].

Both you and Stas have said this, but it's only true if we solely consider C-like languages. Other languages do different things. In the PHP manual, Hack, TypeScript, ActionScript, and most likely other languages (these are just off the top of my head), void functions do still have an implicit result. All of these languages would have had the choice to do what you're suggesting and use null, or its equivalent (undefined for TypeScript and ActionScript). They didn't. Why? If I had to guess, there's at least three reasons. For one, void is the word languages usually use for this. For another, void and null they mean different things. void signifies a function isn't returning anything. null signifies a function that *returns null*, regardless of where that null came from. `function foo(): null { return some_probably_null_returning_function(); } should surely be legal with a null` type hint, yet it's nonsensical code. Finally, making a function truly "return nothing", i.e. disallowing its use as an expression/rvalue, breaks some use cases, like passing along the result of a callback. PHP would neither be the first nor the last to be using void in this way.

If the union types RFC[2] passes it makes sense to allow Foo | null which allows something of type Foo or null. To me it makes sense that if you then remove Foo you are left with null, not void. My personal recommendation because of this would be to use null for the return type and instead of void.

null would be a weird type, because it doesn't make sense as a parameter type, and as a return type, you don't really want to enforce returning null, you want to enforce not returning at all (see the example above). It feels like a poor man's substitute to me. Thanks. -- Andrea Faulds http://ajf.me/