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Date: Thu, 21 Mar 2024 16:30:15 +0000
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Subject: Re: [PHP-DEV] Proposal: AS assertions
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From: imsop.php@rwec.co.uk ("Rowan Tommins [IMSoP]")

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On 21/03/2024 15:02, Robert Landers wrote:
> I don't think you are getting what I am saying.
>
> $a as int|float
>
> would be an int, float, or thrown exception.
>
> $a as int|float|null
>
> would be an int, float, or null.


I get what you're saying, but I disagree that it's a good idea.

If $a is 'hello', both of those statements should throw exactly the same 
error, for exactly the same reason - the input is not compatible with 
the type you have specified.



> Another way of thinking about is:
>
> $x = $a as null
>
> What do you expect $x to be?


The same as $x inside this function:

function foo(null $x) { var_dump($x); }
foo($a);

Which is null if $a is null, and a TypeError if $a is anything else: 
https://3v4l.org/5UR5A


Regards,

-- 
Rowan Tommins
[IMSoP]

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    <div class="moz-cite-prefix">On 21/03/2024 15:02, Robert Landers
      wrote:<br>
    </div>
    <blockquote type="cite"
cite="mid:CAPzBOBOqNT17CRiDsw78GH647xM09z4Y4HpSvM55RXoS-BWfKA@mail.gmail.com">
      <pre>I don't think you are getting what I am saying.

$a as int|float

would be an int, float, or thrown exception.

$a as int|float|null

would be an int, float, or null.</pre>
    </blockquote>
    <p><br>
    </p>
    <p>I get what you're saying, but I disagree that it's a good idea.</p>
    <p>If $a is 'hello', both of those statements should throw exactly
      the same error, for exactly the same reason - the input is not
      compatible with the type you have specified.<br>
    </p>
    <p><br>
    </p>
    <p><br>
    </p>
    <p>
      <blockquote type="cite">
        <pre class="moz-quote-pre" wrap="">Another way of thinking about is:

$x = $a as null

What do you expect $x to be?</pre>
      </blockquote>
    </p>
    <p><br>
    </p>
    <p>The same as $x inside this function:</p>
    <p>function foo(null $x) { var_dump($x); }<br>
      foo($a);<br>
    </p>
    <p>Which is null if $a is null, and a TypeError if $a is anything
      else: <a class="moz-txt-link-freetext" href="https://3v4l.org/5UR5A">https://3v4l.org/5UR5A</a></p>
    <p><br>
    </p>
    <p>Regards,<br>
    </p>
    <pre class="moz-signature" cols="72">-- 
Rowan Tommins
[IMSoP]</pre>
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