On 25 September 2014 09:21, Lester Caine <les...@lsces.co.uk> wrote: > > 'This function returns a unique identifier for the object.' > There is a mistaken view in some usage that that will be DIFFERENT for > different versions of the same object.
Not sure who has that view. It's quite clearly documented, for the lifetime of an object, it will always have the same hash. > So what *IS* returned by spl_object_hash? > The UCN from 7 years ago flags that the identifier is only based on the > internal pointers to the object in memory and that the result is not > user friendly, but without digging into the code, the problems such as > the fact that re-use of the buffer space by a later object cached in the > same buffer may be the same as ID? Yes it is created using various internal pointers, and is about as user-friendly as any other kind of hash. It is possible to create a duplicate hash if you unset an object, force GC collection, and then create a new object which can occupy the same memory location. var_dump(spl_object_hash(new stdClass())); gc_collect_cycles(); var_dump(spl_object_hash(new stdClass())); This is a fairly unrealistic scenario, however Joe Watkins has developed a better hash method that doesn't have this flaw, I don't know if he ever intended to have it applied to core or not. -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
