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Date: Thu, 03 Sep 2020 08:07:44 -0500
To: "php internals" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Draft RFC: foreach iteration of keys without values
From: larry@garfieldtech.com ("Larry Garfield")

On Thu, Sep 3, 2020, at 3:25 AM, Nikita Popov wrote:
> On Thu, Sep 3, 2020 at 10:19 AM Dik Takken <dik.takken@gmail.com> wrote:
> 
> > On 03-09-2020 09:38, Brent Roose wrote:
> > > Hi all
> > >
> > > I want to point out the use-case when you're using CS tools, static
> > analysers and IDEs: they report unused variables as errors. There are ways
> > around those errors, but it's more convenient if there's language support.
> > I'd say that conceptually it's also more correct: if you're not using a
> > variable, it shouldn't be there.
> >
> > Exactly this.
> >
> > The intent of a particular language construct does not only need to be
> > clear to human readers but also to machines. More explicit intent leads
> > to stronger static code analysis tools, which helps us catch more bugs
> > earlier.
> >
> > Regards,
> > Dik Takken
> >
> 
> Static analysis tools don't need a language feature to support this. They
> can recognize the $_ pattern and not emit an unused variable warning for
> it. I'd suggest submitting a feature request.
> 
> Nikita

I agree here.  _ is already a common pattern in other languages for a placeholder ignored variable.  It's not a big jump for PHP static analyzers to start ignoring unused $_ variables, and it requires no language changes or formal standards.

I am skeptical of any performance difference, but from a reader-communication point of view a de facto convention of $_ == unused, and analyzers recognizing that, seems like the path of least resistance.

--Larry Garfield