> From: Soenke Ruempler [mailto:[EMAIL PROTECTED]
> BUT let derived constructors change parameters > a) as constructors are never called from the parent, but > optionally from a child class, it's completely valid IHMO > b) constructors are usally not used in object aggregation / > setters, but called only _ONCE_ at object creation => the > creating code knows the exact (sub-)class and it's constructor. You gave the reason why the restrictions don't apply for constructors (also not in PHP) and probably nobody will change that for "academic reasons" :) Constructors are the special case in OOP as you can call constructors only by instantiating classes. When using them you always refer to a concrete class and never have to deal with polymorphic subtypes (of course constructors can be overloaded in languages that support it). Thus constructors are a place where differences between subtypes tend to pile up so that the LSP holds for the rest of the inherited methods. If you *want* to enforce constructor signatures PHP allows for defining them in interfaces which makes no sense from the academic pov, but may be useful when using the PHP feature of "new $classname($arg)" where you want to make sure first that "$classname instanceof ISomehowConstructable" (where instanceof must take a string as the first operand and work accordingly). Regards, Matthias -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
