Re: [RFC] Generators

On 8/12/12 5:33 PM, Levi Morrison 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?

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/PostOrderIterator.php. An iterator using a generator looks something like:

     public function getIterator() {
         if ($this->left) yield* $this->left;
         yield $this->value;
         if ($this->right) yield* $this->right;
     }

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.

Well, it's 52 lines, not 106. The 5 lines above are not commented nor are they spaced at all like the ones in the class. In the above example, what sets $this->right? or $this->left? There has to be more calling code around this. I don't consider this a very good example. Brian. brianlmoon@php.net