Hi Victor,
It does not contradict because it does not cover two different aspects. First, return types specify
the types of to be returned values. Second, this request proposes a shorthand technique to avoid
writing a single line code multiple times. Third, it is similar to default argument values that are
also typed.
Cheers!
From: Victor Bolshov <crocodile2u@gmail.com>
Sent: Thursday, March 11, 2021 3:00 PM
To: Hamza Ahmad <office.hamzaahmad@gmail.com>
Cc: Rowan Tommins <rowan.collins@gmail.com>; internals@lists.php.net
Subject: Re: [PHP-DEV] Honour the Default Value of 'return' Statement According to the
Function Signature
IMO this feature would contradict with the Single Responsibility Principle. Type hints are for type
hinting, not for value hinting. Cheers.
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On Mar 11 2021, at 10:51 am, Hamza Ahmad <office.hamzaahmad@gmail.com> wrote:
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=(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>
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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