Am 12.03.2015 um 16:57 schrieb Rowan Collins: > Johannes Ott wrote on 12/03/2015 14:51: >> That is nearly like initializing a class constant, but in my opinion a >> constant should not have a "complex" algorithm (For example conditions >> or read from filesystem). That should be encapsulated inside a proper >> method body. > > I agree, but as such, I think that method should be called somewhere by > the code, even if only by a DI container, not happen automagically and > slurp in data from global state. >
It is called somewhere in the code namely inside the static constructor :D > Consider your "prepare some SQL queries" example - it has a dependency > on a database connection, so that now has to be global state; if that in > turn is lazily initialised, it needs to get the connection string from > yet more global state, and so on. By using the class constructor, you > are forced to hard-code those dependencies - there's no parameters to > pass them in, and you can't pre-initialise them from outside the class, > because nothing on the class can run before the class constructor. > Okay that is a point each developer should be aware and decide by his self. >> So doing a null check each time >> is a overhead of calculation which can be avoided with this static >> constructor pattern. > > Presumably the engine would need to perform some implicit equivalent of > "if ( ! self::$initialised )" on each call to decide if the static > constructor needs to be called or not, so the overhead is not completely > eliminated. > Yes you are right but I think it can be done more efficiently inside the interpreter using some struct flags then have to parse each time inside a coded part in the application. > Incidentally, note that a recent RFC to add the ability to declare a > class as static failed by 12 votes to 5 - > https://wiki.php.net/rfc/abstract_final_class - and much of the > discussion was around static implementations being generally inferior to > instances, so I'm not alone in challenging designs that rely on them. > I will check the rfc later but "static class" sounds strange. > Regards, Regards, -- DerOetzi -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
