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Request #69988 foreach ... as long as ...
Submitted: 2015-07-03 12:06 UTC Modified: 2015-08-30 04:22 UTC
From: w-p at dds dot nl Assigned:
Status: No Feedback Package: *General Issues
PHP Version: Irrelevant OS:
Private report: No CVE-ID: None
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From: w-p at dds dot nl
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 [2015-07-03 12:06 UTC] w-p at dds dot nl
Description:
------------
In many languages, as in PHP, the is a loop to iterate over all elements of a collection. Many languages also provide a mechanism to prematurely shut this loop down.

That is odd. By using a foreach loop, the programmer communicates that he will use the loop for all the elements. But he doesn't. A common case is looking for an element in a collection in a way that the collection itself does not support. Upon finding the element, the loop is prematurely terminated.

The problem is that the shut-down of the loop is in fact a go-to statement (go to the first statement after the loop) and severely frustrates refactoring. Exit, break and return statements (the hidden go-to's) cannot be safely taken out of a method and be extracted to another one.

It would be better if there was a loop statement that provides the loop the programmer is actually after: a foreach-with-condition loop. This communicates the intention better, and can always be indented properly (how do you indent a hidden go-to statement?)

Off course, there are more uses than looking up something. Like performing actions on only those elements where it makes sense, for example spell-checking on only those elements that have text. In any case, we would have a structure statement that communicates what the loop is doing.

In the example below, I wrote "as long as" in keywords. This is so unlike the rest of PHP that I expect that a symbol would be less out of place. I am thinking of a questing mark or a double question mark.

Test script:
---------------
$objResult = NULL;
$blnFound = FALSE;
foreach($arrElements => $objElement as long as (! $blnFound)):
        if($objElement->FullName()=='What I am looking for'):
           $objResult = $objElement;
           $blnFound = TRUE;
        endif;
endforeach;
return $objResult;



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 [2015-07-03 23:08 UTC] stas@php.net
-Package: PHP Language Specification +Package: *General Issues
 [2015-08-20 01:19 UTC] kalle@php.net
-Status: Open +Status: Feedback
 [2015-08-20 01:19 UTC] kalle@php.net
That seems like something you can already easily do with a for-loop (given the array is indexed, else use the array functions to advance the internal pointer):

<?php
$found = false;

for($x = 0, $l = sizeof($elements); $x < $l && !$found; ++$x)
{
	if($elements[$x]->getFullName() == 'Rasmus Lerdorf')
	{
		$found = true;
	}
}

if($found)
{
	return($elements[$x]);
}

// ... ??? ...
?>
 [2015-08-30 04:22 UTC] php-bugs at lists dot php dot net
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