On Jun 3, 2006, at 6:12 PM, Jasper Bryant-Greene wrote:
I would imagine that __hash() or whatever it is called would be
defined
on all objects and implemented internally in PHP, and would simply
generate some internal hash that is unique for all objects.
That might work for initial testing, but applying that sort of hash
function to objects identified purely by strings, to take one
example, doesn't work. (in_array(new Str("A"), array(new Str("A")))
is one failure mode that comes instantly to mind. It's inevitable
that two non-identical objects would contain identical data. Think of
the reasons behind C++'s operator==, or for those of you familiar
with Carbon programming under MacOS, the hash callbacks provided by
CoreFoundation's various container types.
Gwynne
SkyTag Software
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