Generator function not executed PHP - php

Question

In the following code, I don't get 'handled' on my output. I see the filehandle a resource, the file gets opened en the contructor of FqReader is called, I checked all that. But with execution of FqReader::getread() I don't see output and the returned array is empty. The first while loop also does not get exectuted when I put while(1) instead of the logic test as in the code now.
<?php
class FastqFile {
function __construct($filename) {
if (substr($filename, -3, 3) == '.gz') {
$this->handle = gzopen($filename, 'r');
return $this->handle;
}
else
$this->handle = fopen($filename, 'r');
return $this->handle;
}
}
class FqReader {
function __construct($file_handle) {
$this->handle = $file_handle;
}
function getread() {
while ($header = fgets($this->handle) !== false) {
echo "handled";
$bases = fgets($this->handle);
$plus = fgets($this->handle);
$scores = fgets($this->handle);
yield array($header, $plus, $scores);
}
}
}
$filename = $argv[1];
$file_handle = new FastqFile($filename);
var_dump($file_handle);
$reader = new FqReader($file_handle);
var_dump($reader->getread());
It outputs:
object(FastqFile)#1 (1) {
["handle"]=>
resource(5) of type (stream)
}
object(Generator)#3 (0) {
}

Answer 1

$file_handle is a FastqFileinstance. Then you pass that object to fgets(), but you need to pass that object's handle to fgets(). For instance:
class FqReader {
function __construct($file_handle) {
$this->handle = $file_handle->handle;
}
function getread() {
while ($header = fgets($this->handle) !== false) {
echo "handled";
$bases = fgets($this->handle);
$plus = fgets($this->handle);
$scores = fgets($this->handle);
yield array($header, $plus, $scores);
}
}
}
The usage of yield was not showing you that error.

Answer 2

Exactly, this works like a charm:
(using a function to open file, not a class)
function openfq($filename)
{
if (substr($filename, -3, 3) == '.gz') {
$handle = gzopen($filename, 'r');
return $handle;
}
else
$handle = fopen($filename, 'r');
return $handle;
}
class FqReader {
function __construct($file_handle) {
$this->handle = $file_handle;
}
function getread() {
while (($header = fgets($this->handle)) !== false) {
echo "handled";
$bases = fgets($this->handle);
$plus = fgets($this->handle);
$scores = fgets($this->handle);
yield array($header, $bases, $scores);
}
}
}
$filename = $argv[1];
$file_handle = openfq($filename);
var_dump($file_handle);
$reader = new FqReader($file_handle);
var_dump($reader->getread());
foreach($reader->getread() as $read) {
var_dump($read);
}