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Date: Sat, 23 Nov 2013 02:03:44 +0800
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To: Leigh <leight@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Power function as operator
From: tjerk.meesters@gmail.com (Tjerk Meesters)

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Hi,


On Sat, Nov 23, 2013 at 1:14 AM, Leigh <leight@gmail.com> wrote:

> Definitely something that is missing and would be a welcome addition.
>
> Where have you placed it in terms of operator precedence?
>

It was equal to the shift operators and left associative, which was most
definitely wrong ;-)

I've now changed the operator precedence to one higher than ~ (bitwise not)
and right associative.

So:
-3 ** 2 == -9
~3 ** 2 == -10,
2 ** 3 ** 2 == 512

I should probably add this in a test case as well =D


> On 22 November 2013 16:58, Tjerk Meesters <tjerk.meesters@gmail.com>
> wrote:
> > Hi,
> >
> > To challenge myself I had tasked myself to introduce a new operator and
> > opcode to the language; now that I'm done with it, I wanted to measure
> the
> > response on the list to actually get it merged before writing an RFC.
> >
> > My work can be found here:
> > https://github.com/datibbaw/php-src/compare/pow-operator
> >
> > It introduces the pow() function as an operator ** (double asterisk), as
> > can be found in languages such as Python (with perhaps the notable
> > difference that it's right associative there).
> >
> > The logic gets exposed via the ZEND_POW opcode and all the logic that
> went
> > into pow() itself is copied into it. The exceptions are that an
> expression
> > such as [] ** 2 (squared empty array) will cause a fatal error because
> the
> > operands are incompatible, whereas pow([], 2) would give 0.
> >
> > Why this operator? Basically because:
> > 1) it's shorter (the keyboard rejoices).
> > 2) it's faster (no ZEND_CALL).
> > 3) it's found in other languages too.
> >
> > I've only implemented one of the test suites; there are quite a few for
> > just one function, but when needed I can add those others as well.
> >
> > Btw, changes to vld aren't pushed yet.
> >
> > Let me know!
> >
> > --
> > --
> > Tjerk
>



-- 
--
Tjerk

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