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Date: Mon, 13 Aug 2012 01:55:23 +0300
Cc: Brian Moon <brian@moonspot.net>,
 Nikita Popov <nikita.ppv@gmail.com>,
 PHP internals <internals@lists.php.net>
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References: <CAF+90c_pRo6Xs2Cv9X-BN3mSnHi65gHHWzD8+yOnAPqgnWJm_w@mail.gmail.com> <50280D37.10109@moonspot.net> <CAFMT4No_qH0aRhbNiNOaomizoedepNd19Utnsq7k5rE3Jn4BwQ@mail.gmail.com>
To: Levi Morrison <morrison.levi@gmail.com>
Subject: Re: [PHP-DEV] [RFC] Generators
From: g.b.yahav@gmail.com (Yahav Gindi Bar)


On 13 =D7=91=D7=90=D7=95=D7=92 2012, at 01:33, Levi Morrison =
<morrison.levi@gmail.com> wrote:

> On Sun, Aug 12, 2012 at 2:08 PM, Brian Moon <brian@moonspot.net> =
wrote:
>> Do you have a good example usage other than a file? I don't find =
fopen/fgets/fclose all that complicated. What are the other valid use =
cases for such a thing?
>=20
> One fabulous use case is creating an iterator for a Binary Search
> Tree.  A post order done without generators looks like:
> =
https://github.com/morrisonlevi/PHP-Datastructures/blob/master/src/Spl/Pos=
tOrderIterator.php.
> An iterator using a generator looks something like:
>=20
>    public function getIterator() {
>        if ($this->left) yield* $this->left;
>        yield $this->value;
>        if ($this->right) yield* $this->right;
>    }
>=20
> This is 5 lines.  The fully commented version of the post-order
> iterator previously mentioned is 106 lines of code and is considerably
> harder to understand.
>=20
> --=20
> PHP Internals - PHP Runtime Development Mailing List
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>=20
Each Iterator implementation in PHP is longer and require a class. The =
yield keyword can reduce the code and make things simpler. If my vote =
count, though I can't believe it is, I'd vote for it - clean syntax, =
make things simpler to develop after you understand the concept (for =
those who against adding because of the learning issue and beginners - =
we'll have beginners anytime that'll mess up with the concept, so I =
don't think that it should restrict us. Put that aside, we should make =
the documentation clear and easy as possible in order to help beginners =
understand the concept).