RE: userdata as table keys
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- Subject: RE: userdata as table keys
- From: "Erik Cassel" <erik@...>
- Date: Mon, 8 Jan 2007 13:30:21 -0800
>
> If the userdata points to the same object why not use the same userdata
> value?
>
Yes, that can be done with some gymnastics (see my workaround suggestion,
and Matt's).
The bottom line (for me) is that Lua has a logical hole because it defines
__eq without a corresponding __hash.
Let's set userdata aside for a minute: You can overload the equality
behavior of two tables by overloading __eq, but the table's behavior as keys
doesn't follow the same rule.
Why not make __hash a part of the language? Would it add a major
performance penalty?