Bug #80010 [Nab]: No error notification or throw when returning iterator from iterator method
Edit report at https://bugs.php.net/bug.php?id=80010&edit=1
ID: 80010
User updated by: petr dot vejchoda at seznam dot cz
Reported by: petr dot vejchoda at seznam dot cz
Summary: No error notification or throw when returning
iterator from iterator method
Status: Not a bug
Type: Bug
Package: Class/Object related
Operating System: Win10
PHP Version: 7.3.21
Block user comment: N
Private report: N
New Comment:
Ok, then tell me, what will happen in case I add foreach ($e as $value) { xy }; Which one will be
actually iterated through? How do I check whether function is iterator method or whether it just
returns Generator. In my case I wrongly typed everything as Iterator, but If I typed it as
Generator, it would be the same. I tried that.
This definitely leads to some very inconsistent behaviour. Or maybe consistently confusing.
This is actually the first time I hear, that methods in PHP return two values. Why in hell would you
allow such a thing with things as confusing as iterator functions.
Previous Comments:
------------------------------------------------------------------------
[2020-08-23 21:17:10] requinix@php.net
https://3v4l.org/bq2df
You didn't say it, but I assume what you're reporting is how the [4]=> output (the one
for $e) is an empty array.
public function secondIterator(\Iterator $first): \Iterator
{
if ($this->whatever === true)
{
return $first;
}
foreach($first as $key=>$value)
{
yield $key => $value * $value;
}
}
Any function that contains a yield will always return a Generator. Always. Even if it returns before
it yields. The return value from a Generator function is kept separate from the yielded values.
https://www.php.net/manual/en/language.generators.syntax.php
https://www.php.net/manual/en/generator.getreturn.php
$e contains a Generator with no yielded items, and its getReturn() will give the passed iterator.
https://3v4l.org/bQJkN
------------------------------------------------------------------------
[2020-08-23 10:07:28] petr dot vejchoda at seznam dot cz
Description:
------------
When writing iterator method, complier lets me return Iterator variable, but it doesn't pass
it. I am actually at version 7.3.20 and I don't care to update. I read changelog.
Note value in $e in supplied code.
Test script:
---------------
class test
{
private $whatever = false;
public function __construct()
{
$a = iterator_to_array($this->firstIterator());
$b = iterator_to_array($this->secondIterator($this->firstIterator()));
$c = iterator_to_array($this->thirdIterator($this->firstIterator()));
$this->whatever = true;
$d = iterator_to_array($this->firstIterator());
$e = iterator_to_array($this->secondIterator($this->firstIterator()));
$f = iterator_to_array($this->thirdIterator($this->firstIterator()));
var_dump([$a, $b, $c, $d, $e, $f]);
}
public function firstIterator(): \Iterator
{
yield 'a'=> 1;
yield 'b'=> 2;
yield 'c'=> 3;
}
public function secondIterator(\Iterator $first): \Iterator
{
if ($this->whatever === true)
{
return $first;
}
foreach($first as $key=>$value)
{
yield $key => $value * $value;
}
}
public function thirdIterator(\Iterator $first): \Iterator
{
if ($this->whatever === true)
{
return $first;
}
return $this->thirdSubIterator($first);
}
public function thirdSubIterator(\Iterator $first): \Iterator
{
foreach($first as $key=>$value)
{
yield $key => $value * $value;
}
}
}
Expected result:
----------------
Returned Iterator should be either passed regularly or iterator method should not be accepted at all
as an iterator method, throwing exception
------------------------------------------------------------------------
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Edit this bug report at https://bugs.php.net/bug.php?id=80010&edit=1
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