Re: when do programs set metatable?

[Doug Rogers <rogers@...>]

Wesley Smith wrote:
> On Feb 8, 2008 6:45 AM, Roberto Ierusalimschy <roberto@inf.puc-rio.br> wrote:
>> More often than not, programs set the metatable of a userdata right
>> after creating the userdata. Does anyone know of relevant counterexamples
>> to this pattern?

> What thoughts are behind this question?  I'm curious.
> best,

Sounds like an optimization for allowing the GC to make assumptions
about metatableless userdata. I wonder what it is.

Would it be possible to deprecate the __gc metamethod and simply provide
a C function to be called in lua_newuserdata()? It actually sounds like
a pretty good idea. To be backwards compatible, though, it would require
a little more work - perhaps the penalty?

The __gc metamethod does seem to be an exceptional case. It is only
available for userdata, which are only available to the C API. Seems
ripe for simplification.

Doug

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