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Date: Fri, 19 Jul 2013 12:39:02 +0200
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To: Chris London <me@chrislondon.co>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Feature Proposal: Allow letter decrementing
From: nikita.ppv@gmail.com (Nikita Popov)

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On Thu, Jul 18, 2013 at 3:46 PM, Chris London <me@chrislondon.co> wrote:

> My friend shared some code with me today that wasn't working for him. He
> was incrementing letters like this:
>
> $letter = 'A';
> echo ++$letter; // Output: B
>
> He was then trying to decrement letters like this:
>
> $letter = 'B';
> echo --$letter; // Output: B
>
> He was really confused why his code wasn't working.  Obviously the answer
> is, PHP doesn't support decrementing letters.
>
> My question is, why specifically doesn't it?
>
> It seems logical that if we support increment we should support decrement.
>
> My proposal:
>
> 1) Support decrementing letters
> - or -
> 2) Throw a notice explaining that decrementing is not supported so
> developers quickly know they can't do that
>
> One hiccup. I imagine maybe the reason we don't support decrementing is
> because what would happen if you tried to decrement 'A'. In that case I
> would suggest either returning NULL or throwing a notice.
>
> Thanks for the input
>
> Chris London
>

I don't think we should add string decrementing due to the rather complex
logic behind it (imho the string incrementing that we have shouldn't be
there either). What we *should* add though is a notice or warning in case
an increment/decrement operation fails. incdec is one of the few places
where we currently silently ignore FAILUREs, instead of throwing some
helpful error message :)

Nikita

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