Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:125485
Feedback-ID: id5114917:Fastmail
Content-Type: multipart/alternative;
 boundary="------------OT6I46SVotyjs0e01PZl4kq0"
Message-ID: <212fd466-85bc-4447-90b7-8fe5426d1bd1@rwec.co.uk>
Date: Mon, 9 Sep 2024 22:35:13 +0100
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PHP-DEV] bikeshed: Typed Aliases
To: internals@lists.php.net
References: <0fa39535-f22d-4eba-b4df-90abe39e683a@app.fastmail.com>
 <e73be2b0-faa9-42eb-a9f6-8308cf4f8c94@app.fastmail.com>
 <ed3847bf-af2e-4e33-ac09-66e44696fdeb@app.fastmail.com>
 <79e58673-50ec-461e-a998-736b020e4287@app.fastmail.com>
 <a3cd6d90-cfac-40d5-a59a-c9f6d9dbe5f0@app.fastmail.com>
 <928A2984-6035-4DA6-9EA7-12E85237C270@php.net>
 <0d461700-1b6c-44fd-9cda-aa698de49847@app.fastmail.com>
 <667233C2-BC47-4530-8142-D90E6907FE63@daveyshafik.com>
 <D95D21CE-45AB-487A-B59D-40305C0C569D@rwec.co.uk>
 <63d241a8-a34a-498c-a5f9-f34230aa5afa@app.fastmail.com>
 <4C7A7F27-B787-44CA-B664-CEF4B9B412FB@newclarity.net>
Content-Language: en-GB
In-Reply-To: <4C7A7F27-B787-44CA-B664-CEF4B9B412FB@newclarity.net>
From: imsop.php@rwec.co.uk ("Rowan Tommins [IMSoP]")

This is a multi-part message in MIME format.
--------------OT6I46SVotyjs0e01PZl4kq0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit

On 09/09/2024 19:41, Mike Schinkel wrote:

> Referencing prior art (e.g. Go) PHP could allow int literals — e.g. `1`, `47`, etc. — to be passed to typedefs derived from ints but require int variables to be typecast to the required type. Same for string literals.

That's an interesting compromise, worth considering.



> In Go you cannot add or subtract on a typedef without casting to the
> underlying type.  I would definitely prefer that to be relaxed, but only
>   if it is relaxed via an explicit opt-in, e.g. something maybe like
> this:
>
> typedef UserId: int operations: +, -, *, /;
> typedef UserName: string operations: .;


I think this would stray into some of the same complexity as operator 
overloads on objects, in terms of the types and values allowed. For 
instance:

typedef Metres: int;

assert( Metres(2) +  Metres(1) === Metres(3) ); // most obvious
assert( Metres(2) + 1 === Metres(3) ); // seems pretty clear

$_GET['input'] = '1';
assert( Metres(2) + $_GET['input'] === Metres(3) ); // might be more 
controversial

typedef Feet: int;
assert( Metres(2) + Feet(1) === Metres(3) ); // almost certainly a bad idea


Not unsolvable, but probably enough scope for nuance and debate that it 
should be left well into Future Scope.


> type MyNewType: Foo
> type MyAlias = Foo

I know this was only an example, but as a general point, I think we 
should avoid concise but cryptic differences like this. PHP is generally 
keyword-heavy, rather than punctuation-heavy, and I think that's a valid 
style which we should keep to.


-- 
Rowan Tommins
[IMSoP]

--------------OT6I46SVotyjs0e01PZl4kq0
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: 8bit

<!DOCTYPE html>
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
  </head>
  <body>
    <div class="moz-cite-prefix">On 09/09/2024 19:41, Mike Schinkel
      wrote:</div>
    <div class="moz-cite-prefix"><br>
    </div>
    <div class="moz-cite-prefix">
      <blockquote type="cite">
        <pre class="moz-quote-pre" wrap="">Referencing prior art (e.g. Go) PHP could allow int literals — e.g. `1`, `47`, etc. — to be passed to typedefs derived from ints but require int variables to be typecast to the required type. Same for string literals. </pre>
      </blockquote>
    </div>
    <div class="moz-cite-prefix"><br>
    </div>
    <div class="moz-cite-prefix">That's an interesting compromise, worth
      considering.<br>
    </div>
    <div class="moz-cite-prefix"><br>
    </div>
    <div class="moz-cite-prefix"><br>
    </div>
    <div class="moz-cite-prefix"><br>
    </div>
    <blockquote type="cite"
      cite="mid:4C7A7F27-B787-44CA-B664-CEF4B9B412FB@newclarity.net">
      <pre>In Go you cannot add or subtract on a typedef without casting to the 
underlying type.  I would definitely prefer that to be relaxed, but only
 if it is relaxed via an explicit opt-in, e.g. something maybe like 
this:

typedef UserId: int operations: +, -, *, /;
typedef UserName: string operations: .;</pre>
    </blockquote>
    <p><br>
    </p>
    <p>I think this would stray into some of the same complexity as
      operator overloads on objects, in terms of the types and values
      allowed. For instance:<br>
    </p>
    <p>typedef Metres: int;<br>
    </p>
    assert( Metres(2) +  Metres(1) === Metres(3) ); // most obvious<br>
    assert( Metres(2) + 1 === Metres(3) ); // seems pretty clear<br>
    <p>$_GET['input'] = '1';<br>
      assert( Metres(2) + $_GET['input'] === Metres(3) ); // might be
      more controversial</p>
    <p>typedef Feet: int;<br>
      assert( Metres(2) + Feet(1) === Metres(3) ); // almost certainly a
      bad idea</p>
    <p><br>
    </p>
    <p>Not unsolvable, but probably enough scope for nuance and debate
      that it should be left well into Future Scope.</p>
    <p><br>
    </p>
    <p>
      <blockquote type="cite">
        <pre class="moz-quote-pre" wrap="">type MyNewType: Foo
type MyAlias = Foo</pre>
      </blockquote>
      <br>
    </p>
    <p>I know this was only an example, but as a general point, I think
      we should avoid concise but cryptic differences like this. PHP is
      generally keyword-heavy, rather than punctuation-heavy, and I
      think that's a valid style which we should keep to.<br>
    </p>
    <p><br>
    </p>
    <pre class="moz-signature" cols="72">-- 
Rowan Tommins
[IMSoP]</pre>
  </body>
</html>

--------------OT6I46SVotyjs0e01PZl4kq0--