Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:105660
MIME-Version: 1.0
Date: Fri, 10 May 2019 14:29:23 +0200
Message-ID: <CANS-=pf=WSJ-X9Sp3dRgrkRcOyK9ZELJ+6AmfpFmWmRgWWxUnw@mail.gmail.com>
To: internals@lists.php.net
Content-Type: multipart/alternative; boundary="00000000000002a749058887b97a"
Subject: PHP header files, restrict to declaring code only
From: kjarli@gmail.com (Lynn)

--00000000000002a749058887b97a
Content-Type: text/plain; charset="UTF-8"

Hello everyone!

This is my first mail to the internals, my apologies if I made a mistake
somewhere.

I would like to propose a new type of php "file" called "phph", short for
"php-header".
This file could receive an optional open-tag: `<?phph` or perhaps a
`declare(header=1)`,
not sure what's more feasible, or if there are better solutions. This open
tag could be
optional for forward compatibility towards omitting the tag.

Php-header files would be allowed to only contain declaring code. This
means that any code
that would run "while loading", would not be allowed and cause a syntax
error in the same
fashion as trying to add a function call in the middle of a class
declaration.

```php
<?php
// forward compatible? change default in a major version?
// any other ideas?
declare(header=1);

// syntax errors:
echo 'foo';
$a = 'b';

// valid
class Foo {}
interface Bar {}
function baz() {}
// etc
```

By restricting it to declaration only, it would make it possible to add
extra features to
classes, such as annotations as there are a lot less edge cases to think
about:

```php
<?php
@trigger_error('Foo is deprecated as of 2.0, use Bar instead',
E_USER_DEPRECATED);
class Foo {}
```

New scenario could be:
```php
<?php
declare(header=1);

use Php\Debugging\Annotations\Deprecated;

@Deprecated('Foo is deprecated as of 2.0, use Bar instead');
class Foo {}
```

This is a pretty rough sketch, and I'm not exactly sure if this is doable.
I'm really eager
to have native support for annotations and perhaps this idea could inspire
someone with a
solution to make this feasible.

Regards,
Lynn van der Berg

--00000000000002a749058887b97a--