>Пятница, 8 октября 2021, 12:14 +03:00 от Kirill Nesmeyanov <nesk@xakep.ru>:
>
>
>
>Hello Internals!
>
>At the moment, there is a feature/bug in the PHP that allows to use
>interpolation of generators.
>
>```
>$code = <<<EXAMPLE
> Hello ${yield}
>EXAMPLE;
>```
>
>I suspect that initially this functionality was not thought out, but it
>partially works, which allows you to implement useful functionality.
>
>```
>[$query, $params] = sql(fn() => <<<SQL
> SELECT * FROM users WHERE id = ${yield 42} OR id = ${yield 0xDEADBEEF}
>SQL);
>
>// Expected
>// $query = "SELECT * FROM users WHERE id = ? OR id = ?"
>// $params = [ 42, 0xDEADBEEF ]
>```
>
>When I say that the functionality was not thought out initially, I mean
>the behavior of generators within strings. For example, the following
>code, which should (seemingly) implement this functionality:
>
>```
>function sql(\Closure $expr)
>{
> [$generator, $params] = [$expr(), $params];
>
> while ($generator->valid()) {
> $params[] = $generator->current(); // Get the value from "yield"
> $generator->send('?'); // Insert placeholder
> }
>
> return [$generator->getReturn(), $params];
>}
>```
>
>Causes an error:
>```
>Warning: Undefined variable $?
>```
>
>That is, the expression "${yield 42}" expects back not the result of
>this expression, but the name of the variable. Therefore, a complete and
>workable implementation of such a functionality is as follows:
>https://gist.github.com/SerafimArts/2e7702620480fbce6c24bc87bfb9cb0e
>
>
>I think it makes sense to do something about it.
>I have two suggestions:
>1) Forbid using "yield" inside strings
>2) Expect not a variable name as a result of this expression, but a
>substitution value.
>
>What do you think?
>--
>Kirill Nesmeyanov
I apologize for the mail duplication. I did not see it receiving on the mailing list (https://news-web.php.net/php.internals) so I sent it again. However, the first came through.
--
Kirill Nesmeyanov
