# Modify language grammar to allow commas to skip defaulted parameters. - Thread: https://externals.io/message/39191 - Original archive: https://news-web.php.net/php.internals/39191 - Started by Richard Quadling on 2008-07-22T14:37:47+00:00 - Messages: 4 - Reply by email to internals@lists.php.net - More for agents: search with https://externals.io/search.md?q={query} · JSON API at https://externals.io/api · documentation at https://externals.io/llms.txt --- ## #39191 — Richard Quadling — 2008-07-22T14:37:47+00:00 URL: https://externals.io/message/39191#39191 2008/7/22 Richard Quadling > > > 2008/7/22 Rodrigo Saboya > > Evan Priestley escreveu: > > […] > Just thinking of other languages that allow you to skip params simply by > using commas. Whilst this isn't supported in PHP, allowing a trailing comma > and skipped parameters could look quite interesting! > > foo(,,,,,,,); > > > I must admit, I get stung with this in JS when I'm building AJAX option > sets through Prototype for IE (I think like arrays in PHP which allow > trailing ,), but I soon learned to do it properly. > > I don't see this as a huge advantage. > > Regards, > > Richard Quadling. > -- > ----- > Richard Quadling > Zend Certified Engineer : http://zend.com/zce.php?c=ZEND002498&r=213474731 > "Standing on the shoulders of some very clever giants!" > Actually, would allowing PHP to skip defaulted parameters be a better facility to add? function foo($opt1 = Null, $opt2 = Null){} foo(,True); Hmm. Doesn't look good does it. But, useful. Having to supply the default value if you don't want to override the default is sort of counter-intuitive. Suppling nothing should equal the default value. Regards, Richard. -- ----- Richard Quadling Zend Certified Engineer : http://zend.com/zce.php?c=ZEND002498&r=213474731 "Standing on the shoulders of some very clever giants!" --- ## #39194 — Christian Schneider — 2008-07-22T15:21:31+00:00 URL: https://externals.io/message/39191#39194 · In reply to: #39191 Richard Quadling wrote: > Actually, would allowing PHP to skip defaulted parameters be a better > facility to add? > > function foo($opt1 = Null, $opt2 = Null){} > > foo(,True); I agree that it would be ugly but possibly useful. OTOH I think it's better to switch to named parameters in such a case anyway. But actually it's orthogonal to the original question whether trailing commas are allowed or not so I'd suggest starting a new thread if you want to change the topic ;-) - Chris --- ## #39358 — david.zuelke@bitextender.com — 2008-07-26T20:50:24+00:00 URL: https://externals.io/message/39191#39358 · In reply to: #39191 Am 22.07.2008 um 16:37 schrieb Richard Quadling: > Actually, would allowing PHP to skip defaulted parameters be a better > facility to add? > > function foo($opt1 = Null, $opt2 = Null){} > > foo(,True); > > Hmm. Doesn't look good does it. But, useful. Having to supply the > default > value if you don't want to override the default is sort of > counter-intuitive. Suppling nothing should equal the default value. That would be totally brilliant, since it means that one wouldn't have to know the default value in order to skip an argument. We looked into this a couple of months ago and the info I got from the engineer that dug into the code was that it would be relatively complicated to implement in the engine (we were considering a keyword back then, sth like foo(default, true);). But if it can be done... I'm all for it. It's definitely useful. David --- ## #39404 — Richard Quadling — 2008-07-28T10:45:53+00:00 URL: https://externals.io/message/39191#39404 · In reply to: #39358 2008/7/26 David Zülke > Am 22.07.2008 um 16:37 schrieb Richard Quadling: > > Actually, would allowing PHP to skip defaulted parameters be a better > > […] > > That would be totally brilliant, since it means that one wouldn't have to > know the default value in order to skip an argument. > > We looked into this a couple of months ago and the info I got from the > engineer that dug into the code was that it would be relatively complicated > to implement in the engine (we were considering a keyword back then, sth > like foo(default, true);). > > But if it can be done... I'm all for it. It's definitely useful. > > David > > Since the inception of SPL, you can use a combination of func_get_args and reflection to gather all the params that the function will use (be they ones that have been supplied or default ones). So, the components are there. I just don't have the C skills to merge these two facilities. I think there needs to be another internal type though. To differentiate between a userland `NULL` being supplied nothing being supplied (VOID ?) I use this userland function to gather all the parameters. function getArgs($s_FunctionOrMethod, array $a_SuppliedParams = array()) { $a_Arguments = array(); // Determine if we are examining a function or a method. // As function names cannot contain ::, we should be OK with this. list($s_Class, $s_Method) = split('::', $s_FunctionOrMethod); if (function_exists($s_FunctionOrMethod) || method_exists($s_Class, $s_Method)) { // Create the appropriate reflector. if (function_exists($s_FunctionOrMethod)) { $rf_This = new ReflectionFunction($s_FunctionOrMethod); } else { $rf_This = new ReflectionMethod($s_Class, $s_Method); } // Shortcut the counts and the parameters. $i_Supplied = count($a_SuppliedParams); $i_Declared = $rf_This->getNumberOfParameters(); $a_Params = $rf_This->getParameters(); // Process the largest number (either Supplied or Declared) for ($i_Arg = 0, $i_Args = max($i_Supplied, $i_Declared) ; $i_Arg < $i_Args ; ++$i_Arg) { // Is this is a Declared param? if ($i_Arg < $i_Declared) { // Determine the parameter name. $s_ParamName = $a_Params[$i_Arg]->getName(); // Get the Default value. if ($a_Params[$i_Arg]->isDefaultValueAvailable()) { $a_Arguments[$s_ParamName] = $a_Params[$i_Arg]->getDefaultValue(); } // Overwrite with the Supplied value if it exists. if ($i_Arg < $i_Supplied) { $a_Arguments[$s_ParamName] = $a_SuppliedParams[$i_Arg]; } // Otherwise this is a Supplied param without a declaration. } else { // Add the Supplied param to the results. $a_Arguments[] = $a_SuppliedParams[$i_Arg]; } } } return $a_Arguments; } I use this as ... $a_Args = getArgs(__METHOD__, `func_get_args()`); inside the method of function. I rely on the fact that __METHOD__ returns something sensible when used in a function. It wouldn't work as is if missed params were allowed. But if `func_get_args()` returned the params keyed to the params position, the gaps in the index/key would signify a missed param. I hope one of the core-devs sees this. Richard. -- ----- Richard Quadling Zend Certified Engineer : http://zend.com/zce.php?c=ZEND002498&r=213474731 "Standing on the shoulders of some very clever giants!"