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Date: Tue, 25 Mar 2025 08:45:23 +0000
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Subject: Re: [PHP-DEV] Feedback for nullc Idea
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From: imsop.php@rwec.co.uk ("Rowan Tommins [IMSoP]")



On 25 March 2025 05:53:30 GMT, Robert Chapin <php@miqrogroove=2Ecom> wrote=
:

>I may have over-simplified the examples=2E=C2=A0 Comparing $input =3D=3D=
=3D 'yes' will have the same result whether $input is null or 'none' or an =
empty string=2E=C2=A0 So not implying a result type, just want to compare a=
 literal or other variable to $input even when not declared=2E


The examples are fine, I think, but perhaps I didn't explain mine clearly =
enough=2E=20

My point is that because null is not going to be coerced by the language t=
o either 'on' nor 'off', there's an implied default depending how you write=
 the expression=2E=20

The following both evaluate to true for an input of 'on', and false for an=
 input of 'off', but give different results for  null:=20

$input =3D=3D=3D 'on'
$input !=3D=3D 'off'

The implied default in the first is 'off', but in the second it's 'on'=2E



>A different example could be if (coalesce($_POST['tick']) > 10) return;


In this case, the implied default is 0=2E It's less risky, because the coe=
rcion from null to int is straightforward=2E The following all imply a defa=
ult of zero:=20

if (coalesce($_POST['tick']) >=3D 10) return;
if (coalesce($_POST['tick']) !=3D 10) return;
if (coalesce($_POST['tick']) !=3D=3D 10) return;

if (coalesce($_POST['tick']) > 0) return;
if (coalesce($_POST['tick']) >=3D 0) return;
if (coalesce($_POST['tick']) !=3D 0) return;

But this doesn't:

if (coalesce($_POST['tick']) !=3D=3D 0) return;


By specifying the default explicitly, we don't have to examine the express=
ion carefully to see what's implied=2E

I don't know if I'd go as far as banning a single-argument coalesce, but I=
 would definitely discourage its use=2E


Rowan Tommins
[IMSoP]