Re: absence of a __hash metamethod

[Miles Bader <miles@...>]

Colin <share-lua@think42.com> writes:
> I would guess that one of the reasons of the missing __hash meta event is
> that it's not that easy to design -- how do you make sure that the __hash
> meta event is "compatible" with the Lua hash function and the other table
> internals?

Not to mention a non-negligible speed hit in a rather critical area of
Lua!  Making table lookups slower makes _everything_ slower.

It would probably be much more acceptable if user-defined __hash hooks
were only used for tables with some flag turned on (which could be
tested very quickly in the C core), with that flag defaulting to off.

-Miles

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