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Date: Thu, 14 Apr 2011 22:41:40 +1000
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To: Jordi Boggiano <j.boggiano@seld.be>
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Subject: Re: [PHP-DEV] Implicit isset/isempty check on short-ternary operator
From: mail_ben_schmidt@yahoo.com.au (Ben Schmidt)

On 14/04/11 10:08 PM, Jordi Boggiano wrote:
> On 14.04.2011 13:58, Ben Schmidt wrote:
>> I have many, many uses for this. E.g. patterns like this:
>>
>> class Foo {
>>     private $defaultBar;
>>     public function foobar(Bar $bar=null) {
>>        $bar = isset($bar) ? $bar : $this->defaultBar;
>>        $bar->doSomething();
>>     }
>> }
>
> I'm sorry but this is not a valid use case, isset() is totally
> unnecessary here. You can use
>
>    $bar = $bar ?: $this->defaultBar;
>
> Of course it still repeats $bar, but it's not that verbose, and will
> work exactly the same as what you do. I'd argue it's even better than
> what you do because, if it weren't for that Bar type hint, if someone
> passes false or "blah" to your function, isset() will return true, and
> you'll try to call doSomething on false/"blah", which is a cute fatal error.

Actually, you'll get a cute fatal error when the function is called
because of the type hint in that case.

Anyway, yeah, sure, perhaps a bad example in its detail. I didn't spend
hours composing it. Just use a little imagination, though, and imagine
that it wasn't a type hinted object coming in, but some other value like
an integer. Then a boolean test would not work (would be false for zero
and erroneously use the default value). You then need the isset test. I
personally prefer to always use an isset/key_exists/is_null test when
I'm testing for something's 'existence' and not its 'truth'. I think
that makes the code more readable.

Ben.