Re: [PHP-DEV] Change yield interpolation behaviour

[Rowan Tommins]

On 08/10/2021 12:21, Christoph M. Becker wrote:

See also
.



A couple of other relevant threads:

* Adding whitespace inside the braces changes the interpretation (note 
that the mentioned behaviour of undefined constants has indeed changed 
in PHP 8.0): https://externals.io/message/92239
* A brief thread about adding a more general interpolation syntax: 
https://externals.io/message/111519



Regards,

--
Rowan Tommins
[IMSoP]

--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: https://www.php.net/unsub.php

Re: [PHP-DEV] Change yield interpolation behaviour

[Christoph M. Becker]

On 08.10.2021 at 12:57, Kirill Nesmeyanov wrote:

> Yes you are right. The same thing happens if you put a function there.
> ```
> function hi(): string
> {
>     return ‘World’;
> }
>  
> echo <<     Hello ${hi()}
> MSG;
> // Warning: Undefined variable $World!
> ```
>  
> For some reason, I did not take this case into account.
>  
> Although it seems to me such semantics are old and require removal from the 
> language, I admit that there is code that uses it and changing the behavior 
> will break a lot. Ideally, I would like to see a similar behavior:
> ```
> echo "Hello ${ $var }"; // Hello World
> echo "Hello ${ 'Wo' . 'rld' }"; // same
> echo "Foo ${ some_foo(42) }";
> echo "Foo ${ 23 + 42 }"; 
> echo "Some ${ ClassName::method() >> 2 ?? $any }";
> // etc
> ```

See also
.

--
Christoph M. Becker

--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: https://www.php.net/unsub.php

Re: [PHP-DEV] Change yield interpolation behaviour

[Kirill Nesmeyanov]

Yes you are right. The same thing happens if you put a function there.
```
function hi(): string
{
    return ‘World’;
}
 
echo <<> 2 ?? $any }";
// etc
```
 
 
>
>Пятница, 8 октября 2021, 12:22 +03:00 от Nikita Popov :
> 
>On Fri, Oct 8, 2021 at 10:55 AM Nesmeyanov Kirill < n...@xakep.ru > wrote:
> 
>> Hello Internals!
>>
>>
>> At the moment, there is a feature/bug in the PHP that allows to use
>> interpolation of generators.
>>
>> ```
>>
>> $code = <<>
>> 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() => <<>
>> 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()];
>>
>> }
>>
>> ```
>>
>> 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.
>>
>This doesn't really have anything to do with yield. ${expr} is PHP's
>general variable-variable syntax, which looks up the variable with name
>returned by expr. The syntax also works inside strings in the form of
>"${expr}". Using "${yield $v}" is just a specific instance of the general
>pattern following the same rules. (This syntax has a special case that
>should be deprecated: "${label}" will be interpreted the same as "$label"
>instead, which is inconsistent with how it works everywhere else. This is
>also why ${yield} without argument will not perform a yield and instead
>look for a variable called $yield.)
>
>PHP unfortunately doesn't have a general expression interpolation syntax,
>you can only interpolate variables and certain variable-like constructs.
>
>Regards,
>Nikita
 
 
--
Kirill Nesmeyanov
 

Re: [PHP-DEV] Change yield interpolation behaviour

[Nikita Popov]

On Fri, Oct 8, 2021 at 10:55 AM Nesmeyanov Kirill  wrote:

> Hello Internals!
>
>
> At the moment, there is a feature/bug in the PHP that allows to use
> interpolation of generators.
>
> ```
>
> $code = <<
>  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() => <<
>  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()];
>
> }
>
> ```
>
> 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.
>

This doesn't really have anything to do with yield. ${expr} is PHP's
general variable-variable syntax, which looks up the variable with name
returned by expr. The syntax also works inside strings in the form of
"${expr}". Using "${yield $v}" is just a specific instance of the general
pattern following the same rules. (This syntax has a special case that
should be deprecated: "${label}" will be interpreted the same as "$label"
instead, which is inconsistent with how it works everywhere else. This is
also why ${yield} without argument will not perform a yield and instead
look for a variable called $yield.)

PHP unfortunately doesn't have a general expression interpolation syntax,
you can only interpolate variables and certain variable-like constructs.

Regards,
Nikita

Re: [PHP-DEV] Change yield interpolation behaviour

[Kirill Nesmeyanov]

  
>Пятница, 8 октября 2021, 12:14 +03:00 от Kirill Nesmeyanov :
> 
>
> 
>Hello Internals!
>
>At the moment, there is a feature/bug in the PHP that allows to use
>interpolation of generators.
>
>```
>$code = << 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() => << 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
 

[PHP-DEV] Change yield interpolation behaviour

[Kirill Nesmeyanov]

 
Hello Internals!

At the moment, there is a feature/bug in the PHP that allows to use
interpolation of generators.

```
$code = << <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

[PHP-DEV] Change yield interpolation behaviour

[Nesmeyanov Kirill]

Hello Internals!


At the moment, there is a feature/bug in the PHP that allows to use 
interpolation of generators.


```

$code = < <valid()) {

       $params[] = $generator->current(); // Get the value from "yield"

       $generator->send('?'); // Insert placeholder

    }

    return [$generator->getReturn()];

}

```

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?

--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: https://www.php.net/unsub.php