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 <[email protected]>
Sent: Thursday, March 11, 2021 1:45 PM
To: [email protected]
Subject: Re: [PHP-DEV] Honour the Default Value of 'return' Statement According
to the Function Signature
On 11 March 2021 03:37:52 GMT, [email protected] 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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