Hello Andrew, did you check out '?:' shortcut in HEAD?
php -r 'echo 4?:2;' -> 4 php -r 'echo 0?:2;' -> 2 best regards marcus Tuesday, September 11, 2007, 3:20:46 PM, you wrote: > If there's a workable proposal for ifsetor() that fixes the concerns > brought up by the original and is likely to go in PHP 6, that would > be great. > In this case, perfect can be the enemy of good. array_get() helps > with many common use cases of ifsetor() while fitting into the the > standard PHP syntax and function model, potentially making its > adoption much easier. > See below for answers to what you mentioned. > On Sep 11, 2007, at 5:27 AM, Marcus Boerger wrote: >> Hello Andrew, >> >> you can easily implement this function run time. It is not very >> flexible >> and far away from what ifsetor was meant to be. Thus I do not think >> it is a >> good idea. See comments below. >> >> marcus >> >> Tuesday, September 11, 2007, 12:12:55 AM, you wrote: >> >>> Here's a patch against HEAD that implements the array_get function >>> previously suggested on this list. I also attached a test suite, >>> which should go in ext/standard/tests/array/array_get.phpt. Feedback >>> is welcome. >> >>> Independently, someone else had posted the same idea as a feature >>> request for PHP 5, and if there's interest I can backport it. >> >>> 40792 Open Wish: Function array_get(&$mixed, $key, >>> $defaultvalue) >> >>> /* Prototype: >>> * mixed array_get ( array $search, mixed $key, mixed $default ); >> >> array should not be passed as reference as that would be a slowdown >> unless >> the function is supposed to create the index key which according to >> the >> specs below it doesn't. > True, as you suggest, it is not passed by reference. (That bug title > was posted independently by someone who might not have thought that > particular aspect through, and it isn't important to the text.) >> >>> * Description: >>> * Returns the value corresponding to the given key if the key exists >>> * in the array. $key can be any value possible for an array index. >>> * If the key does not exist, the function returns $default, or FALSE >>> * if $default is not specified. Also works on objects. >>> * Similar semantics to array_key_exists. >>> */ >> >>> Here is the original proposal: >>> ======= >>> array_get, a more palatable alternative to ifsetor >> >> Things this cannot do but ifsetor can. >> - Check whether the array exists > True, though there's an argument that this could even be better (less > error-prone) for the typical uses I've seen in my code and elsewhere, > where we're interested in whether the key exists in an array we > already have. An isset-like function doesn't allow you to separate > the two existence checks, allowing spelling errors in the array name > to go undetected when they could easily be caught. In circumstances > where you really do need to check both, you can call isset() or !empty > () on the array first: > $value = isset($array) ? array_get($array, 'mykey') : FALSE; >> - Mulitlevel queries > Use nested array_get(). >> - Other types of queries (e.g. object members) > array_get() supports object members, just like array_key_exists(). >> - In theory we could have ifsetor even return a writeable reference >> where a >> non existing key would either be created or (pretty bad imo) a >> reference to >> the default value gets returned. > Something like that would be nice, but it doesn't exist and I haven't > seen a concrete proposal for it. >> >>> MOTIVATION >> >>> There is an unmet need for an accessor that doesn't generate an >>> E_NOTICE when the value is missing, as shown by ongoing discussions >>> and repeated requests for an ifsetor operator. However, ifsetor had a >>> special-case syntax and generally didn't fit very well with the rest >>> of the language. >> >>> http://devzone.zend.com/node/view/id/1481#Heading2 has a brief >>> summary. See the Related Functions and Proposals section for more. >> >>> Reading over those ideas (firstset(), coalesce(), :?, ifset(), and a >>> workaround using settype()), most of the best uses boil down to >>> retrieving values from arrays. >> >> >>> PROPOSAL >> >>> As a simpler alternative to constructs such as this common double >>> array reference... >>> >>> $value = isset($_POST['command']) ? $_POST >>> ['command'] : ''; >>> >>> I propose an array_get function, like this... >>> >>> $value = array_get($_POST, 'command', ''); >>> >>> The third argument provides a default. This function would require no >>> special syntax, and makes a very common construct easier to read and >>> less error-prone to type. It's a concise way of saying that missing >>> values can be handled gracefully. >> >>> Though request processing was used as an example, the function has >>> wide applicability across many other uses of associative arrays. >> >>> >>> GREAT, BUT WHY NOT ADD IT TO AN INCLUDE FILE, INSTEAD OF THE CORE? >> >>> One of the goals is to make everyday PHP code simpler and clearer. >>> Writers of sample code snippets should be able to rely on array_get() >>> being available. Otherwise, they will not use it. Clearer sample code >>> particularly benefits beginners, who would probably find array_get >>> easier to understand, but anyone else who has to read or maintain >>> other people's code would benefit from its wide deployment in core as >>> well. The function is generally useful enough to be part of the >>> language, and the implementation in C is also more efficient than a >>> PHP version. >> >>> That said, a compatibility function for older versions of PHP is >>> given below. >> >> >>> SEMANTICS >> >>> mixed array_get(array $array, mixed $key[, mixed >>> $default = FALSE]); >>> >>> If $array contains the key $key, $array[$key] is returned. Otherwise >>> $default is returned. >>> >>> If $default is not specified, it defaults to FALSE. (NULL would also >>> be possible, and would more closely match other languages such as >>> Python with its dict.get method, but other PHP functions tend to >>> return FALSE to indicate no value.) >>> >>> The semantics match >>> >>> array_key_exists($key, $array) ? $array[$key] : >>> $default >>> >>> ... but for comparison, >>> >>> isset($array[$key]) ? $array[$key] : $default >>> >>> is subtly different. The preferred array_key_exists version has these >>> differences: >>> 1. If $array[$key] exists but has been set to null, that >>> null >>> value will be returned instead of $default. This is likely to be the >>> least surprising thing to do. >>> 2. If $array itself is unset, an error is generated. >>> This is good. >>> The intention is to gracefully handle a missing $key. But if even >>> $array itself doesn't exist, there may be another problem, such as >>> misspelling the array variable. isset() ignores all errors, sweeping >>> more under the rug than we typically want. >> >> >>> IMPLEMENTATION >> >>> A core C implementation of array_get() benchmarked between two and >>> three times as fast as the implementation in PHP. I'll attach the >>> patch after responding to feedback. >> >>> See the last section for the code of the PHP implementation. >> >> >>> RELATED FUNCTIONS AND PROPOSALS >> >>> This function is different than the array_get function proposed and >>> rejected in http://bugs.php.net/bug.php?id=28185. That function had >>> no default value and throws a notice when the key doesn't exist, >>> eliminating the major purpose of this function. >> >>> The ?: operator doesn't serve the same purpose, because it causes an >>> E_NOTICE for missing values. However, ?: and array_get can be used >>> together to provide short-circuit evaluation, overcoming the >>> limitations of both. See the LIMITATIONS section for an example. >> >>> ifsetor: as discussed above, ifsetor wasn't a regular function. It >>> required special language syntax support because it attempted to test >>> whether a direct parameter itself was set or unset, and was >>> ultimately rejected. >> >>> ifset: a related proposal to ifsetor, with a simpler syntax, ifset >>> was missing a way to control the default value. >> >>> See here for more discussion about the 'E_STRICT ternary pain-in-the- >>> ass expression' and alternatives: >>> http://keithdevens.com/weblog/archive/2005/Nov/24 >>> http://www.php.net/~derick/meeting-notes.html#id39 >>> http://devzone.zend.com/node/view/id/1481#Heading2 >> >>> >>> LIMITATIONS >> >>> This proposal doesn't address every requested feature. The third >>> parameter is always evaluated, so calling a slow function there would >>> be undesirable. However, the limitation appears to be unavoidable >>> without special language support, and there are workarounds. These >>> snippets have approximately equal meanings (though they may differ is >>> the handling of array values that convert to false): >> >>> array_get($_GET, 'foo', slowDefaultCalculation()) >> >>> $val = array_get($_GET, 'foo'); if (!$val) $val = >>> slowDefaultCalculation(); >> >>> array_get($_GET, 'foo') ?: slowDefaultCalculation() >> >>> The last example uses the new PHP 6 ?: operator. >> >>> This function applies only to array elements. Unlike other proposed >>> functions, it doesn't also attempt to determine whether variables are >>> set. However, the practical uses suggested for the other functions >>> generally ended up applying to array elements. >> >> >>> COMPATIBILITY FUNCTION FOR OLDER VERSIONS OF PHP >> >>> if (!function_exists('array_get')) { >>> function array_get($arr, $key, $default = false) { >>> if (array_key_exists($key, $arr)) { >>> return $arr[$key]; >>> } >>> else { >>> return $default; >>> } >>> } >>> } >> >>> (This version turned in the fastest times out of several variants. >>> Passing $arr by reference or attempting to return the result by >>> reference had a huge negative impact, and using the ternary ? : >>> operator instead of the if/else was slightly slower.) >> >>> ======= >>> -- >>> Andrew Shearer >>> http://ashearer.com/ >> Best regards, >> Marcus > Andrew Shearer > http://ashearer.com/ Best regards, Marcus -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
