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To: "'Rowan Tommins'" <rowan.collins@gmail.com>,
	<internals@lists.php.net>
References: <01fa01d71627$edb078a0$c91169e0$@gmail.com> <0DC08797-11DD-4D45-8C43-5678822DA259@gmail.com>
In-Reply-To: <0DC08797-11DD-4D45-8C43-5678822DA259@gmail.com>
Date: Thu, 11 Mar 2021 14:51:21 +0500
Message-ID: <000f01d7165c$1923ae10$4b6b0a30$@gmail.com>
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Subject: RE: [PHP-DEV] Honour the Default Value of 'return' Statement According to the Function Signature
From: office.hamzaahmad@gmail.com ("Hamza Ahmad")

Hi Rowan,
Thanks for the response. Luckily, you razed the question that I thought =
about after posting the first request.
My idea develops on respecting both return type hints and union types. =
The current implementation of empty return does not respect the function =
signature. As I have mentioned in the first message that empty return =
returns null regardless of the return type set, I propose that an empty =
return may return the defaults of types i.e. an empty string if the type =
is string, an empty array if the type is array, zero if the type is int =
etcetera. I have also noted that in a void typed function, an empty =
return may return nothing and just end the execution.
The current implementation of empty return is only favourable for mixed =
type. In other words, when the return type is mixed, an empty return may =
return null. Otherwise, it should respect the declared return type.
After the release of union types, there emerges a question regarding the =
selection of default return value. To solve this problem, the type on =
the very right side will be used.
Now, I come to your question, Rowan. As of today, only false and null =
literals are supported. If both assist in error handling, why does empty =
return always returns null?
I tested this code on shell.
var_dump($a=3D(function():string|false{return;})());
It produced:
Fatal error: A function with return type must return a value in php =
shell code on line 1.
Here comes the inconsistency. To resolve the problem, I suggest to =
respect the literals first. If literals are not found, respect the first =
type on the right side.
Moreover, only two standalone literals, false and null,  will be =
supported. Otherwise, the literal should be one of the types specified. =
If multiple literals are specified, it will throw an error of multiple =
literals. The literal can be a simple literal, such as, "unknown" 0, and =
a constant expression, like self :: MSG_UNKNOWN. It will help maintain =
the multi-language scripts.
I hope I have been able to make my stance clear.
Best
Hamza Ahmad

-----Original Message-----
From: Rowan Tommins <rowan.collins@gmail.com>=20
Sent: Thursday, March 11, 2021 1:45 PM
To: internals@lists.php.net
Subject: Re: [PHP-DEV] Honour the Default Value of 'return' Statement =
According to the Function Signature

On 11 March 2021 03:37:52 GMT, office.hamzaahmad@gmail.com wrote:
><?php
>function get_nationality_string(int $country_code) : string | "unknown"
>{
>	return;
>};

If I understand you correctly, your idea is that the "return;" here =
would be treated automatically as "return 'unknown';" I think that's an =
interesting idea, although I can't immediately think of a situation =
where I'd use it.

My main concerns are with the syntax:

- Firstly, specific literals aren't currently allowed in return types, =
and allowing them would have other implications. Three exception is =
"false", which is allowed because of its common use as an error code, =
including in many internal functions.
- Secondly, it could be ambiguous which is intended to be the default =
value, if the return type was something like int|"yes"|"no"

Perhaps the default return value would need to be specified separately =
from the return type somehow?

Regards,
Hi Hamza,

Welcome to the list, and thanks for sharing this idea.

--
Rowan Tommins
[IMSoP]

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