Re: Re: Enforce a constant in a class.

2010/1/25 Pete Ford <pete@justcroft.com>: > Richard Quadling wrote: >> >> 2010/1/22 Pete Ford <pete@justcroft.com>: >>> >>> IMHO, a constant is not the correct beastie in this case - if you want it >>> to >>> be different depending on the implementation then it ain't a constant! >>> >>> You should probably have protected static variables in the interface, and >>> use the implementation's constructor to set the implementation-specific >>> value (or override the default) >>> >>> interface SetKillSwitch >>> { >>>       protected static $isSet = TRUE; >>>       protected static $notes; >>>       protected static $date = '2010-01-22T11:23:32+0000'; >>> } >>> >>> class KilledClass implements SetKillSwitch >>> { >>>       public function __construct() >>>       { >>>               self::$isSet = FALSE; >>>               self::$date = '2010-01-21T09:30:00+0000'; >>>               self::$notes = "Test"; >>>       } >>> } >>> >>> Cheers >>> Pete Ford >> >> And of course, "Fatal error: Interfaces may not include member variables". >> >> >> > > Ooops, sorry :) > > I tend to end up using abstract base classes rather than interfaces for that > sort of reason... > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, visit: http://www.php.net/unsub.php > > Essentially I was starting with the idea that a subclass with constant X _MUST_ have constant Y and Z. That's what I wanted to enforce. But, finding that defined() was enough, I now realize that Y and Z are _not_ mandatory, but they are constants. So simply ... $KillSwitchNotes = defined(get_called_class() . '::KILL_SWITCH_NOTES') ?: Null; is enough and now the whole _MUST_ is gone and is now optional. Much better. Thank you to everyone who chipped in. Old dog should really have known that old trick! -- ----- Richard Quadling "Standing on the shoulders of some very clever giants!" EE : http://www.experts-exchange.com/M_248814.html EE4Free : http://www.experts-exchange.com/becomeAnExpert.jsp Zend Certified Engineer : http://zend.com/zce.php?c=ZEND002498&r=213474731 ZOPA : http://uk.zopa.com/member/RQuadling