PHP equivalent to Python's yield operator

There is a rfc at https://wiki.php.net/rfc/generators adressing just that, which might be included in PHP 5.5.

In the mean time, check out this proof-of-concept of a poor mans "generator function" implemented in userland.

namespace Functional;error_reporting(E_ALL|E_STRICT);const BEFORE = 1;const NEXT = 2;const AFTER = 3;const FORWARD = 4;const YIELD = 5;class Generator implements \Iterator {    private $funcs;    private $args;    private $key;    private $result;    public function __construct(array $funcs, array $args) {        $this->funcs = $funcs;        $this->args = $args;    }    public function rewind() {        $this->key = -1;        $this->result = call_user_func_array($this->funcs[BEFORE],                                              $this->args);        $this->next();    }    public function valid() {        return $this->result[YIELD] !== false;    }    public function current() {        return $this->result[YIELD];    }    public function key() {        return $this->key;    }    public function next() {        $this->result = call_user_func($this->funcs[NEXT],                                        $this->result[FORWARD]);        if ($this->result[YIELD] === false) {            call_user_func($this->funcs[AFTER], $this->result[FORWARD]);        }        ++$this->key;    }}function generator($funcs, $args) {    return new Generator($funcs, $args);}/** * A generator function that lazily yields each line in a file. */function get_lines_from_file($file_name) {    $funcs = array(        BEFORE => function($file_name) { return array(FORWARD => fopen($file_name, 'r'));   },        NEXT   => function($fh)        { return array(FORWARD => $fh, YIELD => fgets($fh)); },        AFTER  => function($fh)        { fclose($fh);                                       },    );    return generator($funcs, array($file_name));}// Output content of this file with padded linenumbers.foreach (get_lines_from_file(__FILE__) as $k => $v) {    echo str_pad($k, 8), $v;}echo "\n";

PHP has a direct equivalent called generators.

Old (pre php 5.5 answer):

Unfortunately, there isn't a language equivalent. The easiest way is to either to what you're already doing, or to create a object that uses instance variables to maintain state.

There is however a good option if you want to use the function in conjunction with the foreach-statement: SPL Iterators. They can be used to achieve something quite similar to python generators.

I prototype everything in Python before implementing in any other languages, including PHP. I ended up using callbacks to achieve what I would with the yield.

function doSomething($callback) {    foreach ($something as $someOtherThing) {        // do some computations that generates $data        call_user_func($callback, $data);    }}function myCallback($input){    // save $input to DB     // log    // send through a webservice    // etc.    var_dump($input);}doSomething('myCallback');

This way each $data is passed to the callback function and you can do what you want.